The UN security council has called for an immediate end to attacks by Yemen’s Houthi rebels on shipping in the Red Sea, adopting a resolution despite abstentions from Russia and China.

The resolution also called on the Houthis to release the Galaxy Leader, a Japanese-operated vehicle carrier linked to an Israeli businessman that the group commandeered on 19 November, along with its 25 crew.

US Central Command said there had been 26 Houthi strikes on shipping since then, causing shipping companies to bypass the route and divert around South Africa’s Cape of Good Hope, significantly adding to journey times and cost.

An attack and boarding of the St Nikolas off the Oman coast, reported hours after the UN security council passed its resolution, is yet to be identified and may be the work of Iranians, not the Houthis based in Yemen.

On Wednesday, Antony Blinken, the US secretary of state, said further attacks could prompt a western military response. He was speaking after US and British warships on Tuesday shot down 21 drones and missiles fired by the Houthis, in what London called the largest such attack in the area.

The British defence secretary, Grant Shapps, said the UK, its western allies and Saudi Arabia were “all agreed” that the series of attacks on warships and merchant shipping in the southern Red Sea “cannot continue”. He did not rule out striking Houthi military targets on land.

The Houthis, an Iran-aligned group that seized much of Yemen in a civil war, have vowed to attack ships linked to Israel or bound for Israeli ports to show support for Hamas in its war in Gaza. However, many of the targeted ships have had no links to Israel.

On Thursday, Israel was to face the international court of justice to defend itself against accusations of genocide in Gaza. The initial hearings will focus on requests from South Africa – which brought the case – for emergency measures ordering Israel to suspend its military actions in Gaza while the court hears the merits of the case, a process that could take years.

A key provision of Wednesday’s security council resolution, which was sponsored by the US and Japan, noted the right of UN member states, in accordance with international law, “to defend their vessels from attack, including those that undermine navigational rights and freedoms”.

The provision amounted to an implicit endorsement of Operation Prosperity Guardian, a US-led multinational naval taskforce that has been defending commercial ships in the Red Sea and Gulf of Aden from Houthi missile and drone attacks.

A Houthi spokesperson in Yemen dismissed the resolution as a “political game” and said the US was the one violating international law.

The council’s adoption of the resolution came after it rejected amendments proposed by Russia that would have stripped out the implicit endorsement of the US-led taskforce and included the war in Gaza among the “root causes” of the Houthi strikes.

The Russian ambassador, Vassily Nebenzia, questioned the legitimacy of the taskforce and said the resolution as drafted was “an open-ended blessing of it”.

Despite possessing a veto power in the security council, Russia and China both chose to abstain from the vote, along with Mozambique and Algeria.

The resolution, noting the “large-scale” violations of an arms embargo against the Houthis, also reiterates the need for all member states to “adhere to their obligations” and “condemns the provision of arms” to the Houthis.

Washington’s UN ambassador, Linda Thomas-Greenfield, said: “Iran has long encouraged the Houthis’ destabilising actions in the region through both financial and materiel support.”

The UN earlier said it continued “to be very concerned about the situation in the Red Sea, not only because of the situation itself, and the risks that it causes to global trade”.

A report this week from Windward, a Maritime analysis company, showed that since the Houthis began their attacks on the Red Sea, the number of passages through the vital shipping lane had dropped considerably.

In the second week of December, there was a 70% decrease in container vessels passing through the southern entrance to the Red Sea, the Bab al-Mandeb strait, compared with the 2023 weekly average. At the same time, there was a 136% increase of voyages through the Cape of Good Hope.

Analysts and government officials have said the continued disruption to maritime commerce could lead to increased energy and food prices.

In the case of the attack on St Nikolas, the UK Maritime Trade Organisation (UKMTO) on its social media account said four to five masked men wearing military-style uniforms and masks had boarded a ship 50 nautical miles east of the port of Sohar, an area that has not been subject to attacks by Houthis before. The group had covered the surveillance cameras on board.

The maritime security firm Ambrey said the ship had been prosecuted in the past for carrying Iranian oil, which falls under sanctions, adding that the tanker was heading in the direction of Bandar-e-Jask, Iran.

Spokespeople for the ship’s Greek managers, Empire Management, said they had lost contact with the ship and its 19 largely Filipino crew. “The vessel had loaded the previous days in Basrah [Iraq] a cargo of about 145,000 MTs of crude oil destined to Aliaga [Turkey], via the Suez Canal. The charterer of the vessel is Tupras,” they said.

UKMTO urged shipping to proceed with caution.

Reuters and Agence France-Presse contributed to this report