MPS are to discuss the “very serious and concerning breach” of parliamentary data after a document containing confidential details about their staff was wrongly posted online.

Ever since the murder last summer of Yorkshire MP Jo Cox, the concern about the publication of MPs’ and their staff’s personal data, including travel patterns, has grown.

Earlier this year, it emerged that Angus Robertson, the SNP’s Westminster leader, had ordered his colleagues to stop submitting mileage expenses in Parliament to protect their travel patterns.

On Friday, the Independent Parliamentary Standards Authority[Ipsa], which is responsible for MP’s pay and expenses, said the document was uploaded in error on an old website on Thursday night.

It included confidential personal information about MPs' staff names, salaries, rewards, working patterns and holiday entitlements.

In a letter to MPs, Marcial Boo, Ipsa’s Chief Executive, said the document was taken down within an hour of the watchdog becoming aware of the issue.

He said that it was thought to have been accessible online for a period of around four hours.

"We take information security very seriously and the safety and security of MPs and their staff is a priority.

"An investigation is currently underway and we have notified the Information Commissioner. We will be writing directly to all of those affected.”

Mr Boo stressed: "I sincerely apologise to you for the distress this has caused."

While the Ipsa chief acknowledged the error represented a "serious data breach", he made clear no information relating to the security of the individuals affected was made public.

"No addresses, no bank account details, no phone numbers, and no National Insurance numbers were disclosed. However, we recognise that this was still extremely sensitive personal information," he added.

Pete Wishart, the SNP MP for Perth, said he would be raising the matter on the Speaker’s Committee, which oversees budgetary matters at Westminster.

He told The Herald: “This is a very serious and concerning breach of data. We need to know if there is any traceability about those details to people’s addresses.

“Ipsa seems to be confident it’s just MPs’ staff data that has been affected but we have a duty of care to our staff. This is definitely something the committee will want to examine,” Mr Wishart added.

The watchdog was set up in the wake of the 2009 MPs' expenses scandal so that parliamentarians were no longer responsible for setting their own pay and conditions.

It quickly faced a backlash from some MPs with complaints of late payments and an overly complicated computer system.

It faced further controversy in 2015 when it handed MPs a 10 per cent pay rise - taking their annual salary from £67,000 to £74,000 - at a time of public sector pay restraint.