The Department of Foreign Affairs has advised Australians to return home as soon as possible by commercial means because overseas travel is becoming “more complex and difficult” as countries impose travel restrictions and close their borders.

The new travel advice, issued on Tuesday night, triggered speculation that the Morrison government could be about to impose a lockdown in Australia. But officials told Guardian Australia that was not in contemplation.

Governments are poised to unveil new social distancing measures after a meeting between Scott Morrison and the premiers on Tuesday night. Leaders discussed additional restrictions on indoor gatherings and new measures for the aged care sector and remote Indigenous communities.

As well as the efforts to slow community transmissions of the illness, the Morrison government is also preparing a second multibillion-dollar “safety net” package. The Coalition is considering a boost to income support for welfare recipients and support for businesses at risk as a consequence of economic shock associated with the coronavirus.

While a second round of pump priming is being prepared, senior ministers on Tuesday warned the extra spending will not be enough to avoid widespread job losses stemming from the Covid-19 health crisis.

The health minister, Greg Hunt, on Tuesday also flagged a massive scaling up of public testing for the disease amid concern over test kit shortages, saying he will make a “major announcement” on the country’s testing regime on Wednesday.

According to the Department of Health, the global shortage of test kits is the reason behind the government’s decision to undertake targeted, rather than widespread testing.

The new Dfat travel advice asks Australians to reassess all overseas travel if it is non-essential, and it says: “If you’re already overseas and wish to return to Australia, we recommend you do so as soon as possible by commercial means”.

Given more and more countries are closing their borders or introducing travel restrictions, Dfat advised people may not be able to return to Australia when they need to. “If you decide to return to Australia, do so as soon as possible. Commercial options may become less available,” Dfat said.

The department said the advice had been adjusted because there may be a higher risk of contracting the virus overseas and “you may come in contact with more people than usual, including during long-haul flights and in crowded airports”. It says health systems in some countries “may come under strain and may not be as well-equipped as Australia’s or have the capacity to support foreigners”.

“Overseas travel has become more complex and unpredictable. Many countries are introducing entry or movement restrictions. These are changing often and quickly. Your travel plans may be disrupted. You may be placed in quarantine or denied entry to some countries, and you may need to self-quarantine on return to Australia”.

“Think about what this might mean for your health, and your family, work or study responsibilities”.

As of Tuesday, there are 438 confirmed cases of the virus in Australia, with a third federal politician – the Liberal senator Andrew Bragg – among the latest to test positive to the disease.

Three senators who attended a committee hearing with Bragg last week – Jenny McAllister, Tony Sheldon and Rex Patrick – are now in self-isolation.

The rapidly escalating crisis has prompted the Coalition to hastily develop another wave of economic stimulus, which is expected to be more far-reaching than the $17.6bn package announced last week.

Federal cabinet discussed options in a meeting on Tuesday, with the measures also discussed by the cabinet’s expenditure review committee, however it is understood no final decisions have been made.

The government is looking at ways to ramp up support through existing programs and mechanisms, but the package is unlikely to be announced until after the Reserve Bank of Australia intervenes again on Thursday either through another emergency rate cut or a significant purchase of government bonds.

It is expected the government will put the new measures to a scaled-down parliament next week to be voted on before the Easter break and the May budget.

It is possible the government will also a deliver a separate assistance package for airlines in advance of unveiling the second round of stimulus either at the weekend or early next week. Qantas has signalled it will close 90% of international flights and 60% of domestic flights from the end of the month.

The government and the opposition have agreed that only 90 of the country’s 151 MPs will come to Canberra for the next parliamentary session, along with 54 of the country’s 76 senators.

The package is expected to target both heavily affected industries as well as vulnerable low-income earners.

However, even with the extra billions of dollars in government support, the finance minister, Mathias Cormann, warned that the “grim reality” was that jobs would be lost as the country faced an “unprecedented” economic shutdown.

“We are very conscious that as we are looking at things today, that many businesses will close and many Australians will lose their jobs,” Cormann said on Tuesday.

“We will ensure that they have got the appropriate levels of support through this transition to the other side when there will be a strong bounce back and a strong recovery.”

The finance minister also revealed that the government was looking at specific measures to help vulnerable low-income earners, who he conceded would be hard hit by a downturn.

“We are very seriously considering what appropriate supports we can provide, in particular to the most vulnerable across our community and specifically those that are most severely impacted,” Cormann said.

“This is going to be a tough period. There will be a strong recovery on the other side, but it is going to be a tough period. We are all in this together. We are going to come up with the best possible way to get ourselves through this period.”

Amid calls for the government to do more to protect casual workers, the minister for industrial relations, Christian Porter, said the existing social safety net was the best delivery mechanism “for those who will need help in the challenging times ahead”.

“But however many people may require help in the challenging times ahead, because they find they are not able to work or because they have experienced unemployment due to changed economic conditions, the best assistance mechanism is the welfare system because of its proven ability to deliver income support to affected workers,” Porter told Guardian Australia.

“This is the most effective way to ensure income support reaches those in need as simply and quickly as possible, with regular waiting periods waived.”

Porter said that while the government was not considering “wholesale structural change” to the industrial relations system, those most affected needed “income support until things improve”.

The Australian Chamber of Commerce and Industry chief executive, James Pearson, called on the government to offer more support for anyone in the workforce who has to self-isolate without access to an income – including both employees and small business people.

“Many businesses are paying to cover periods in isolation, even where there is no legal obligation to do so,” Pearson said.

“But small, family-owned businesses struggling to survive, let alone retain the staff they have, do not have the resources to support additional payments for casuals.”