Some HSBC customers have been locked out of their mobile banking services, as MPs launched a formal inquiry into banking IT failures following a string of service disruptions this year.

A spokeswoman for the bank said customers were intermittently prevented from signing on to the mobile app, but online banking via browsers had been operating as normal.

The issues were first reported at about 8.20am on Friday, with services restored at about 2pm. HSBC was not able to confirm how many customers were affected.

“We apologise for any inconvenience this may have caused,” the bank said.

It is the fourth time this month that HSBC has been forced to apologise to customers over mobile or online banking disruptions, with outages also logged on 6, 16 and 18 November.

The latest problem came as MPs on the Treasury select committee, in an embarrassing coincidence for HSBC, launched a formal inquiry into banking IT failures, after glitches at Barclays, TSB and Visa affected key services for millions of customers this year.

The committee chairwoman, Nicky Morgan, said: “The number of IT failures at banks and other financial institutions in recent years is astonishing. Since becoming chair of the committee 16 months ago, there have been problems at Equifax, TSB, Visa, Barclays, Cashplus and RBS, to name a few.

“Millions of customers have been affected by the uncertainty and disruption caused by failures of banking IT systems. Measly apologies and hollow words from financial services institutions will not suffice when consumers aren’t able to access their own money and face delays in paying bills.

“As bank branches close and customers are ushered towards online services, the availability of those services is vital.”

Figures recently compiled by the consumer group Which? showed the UK has lost nearly two-thirds of its bank and building society branches over the past 30 years, as companies plough ahead with cost cuts and digital banking drives.

The number of branches has dropped from 20,583 in 1988 to 7,586, leaving more customers to rely on online services susceptible to IT blunders.

RBS and Barclays – which have closed 424 and about 200 branches respectively over the past year – both experienced IT service disruptions in September that affected online banking customers.

HSBC has not closed any branches this year, but customers are still adjusting to a restructuring programme under which the bank reduced its branch network by nearly 400.

TSB’s IT meltdown was one of the most high-profile cases in the UK, costing the challenger bank £250m and thousands of lost customers. It had been working to move accounts from an IT system inherited from the bank’s previous owner, Lloyds Banking Group, to one owned and created by its Spanish owner, Sabadell, back in April.

The botched migration locked millions of customers out of their accounts and caused prolonged disruption for account holders.