Rishi Sunak said he is committed to the triple lock on state pensions although he swerved calls to guarantee it will feature in the next Conservative manifesto.

The triple lock guarantees an increase of the state pension in line with average earnings, inflation or 2.5%, whichever is highest.

Ministers are currently considering whether to strip out the impact of public sector bonuses on the earnings figure, which could mean an increase of around 7.8% rather than 8.5% from April, potentially saving the Government hundreds of millions.

SNP Westminster leader Stephen Flynn mocked Mr Sunak at Prime Minister’s Questions as he told the Commons: “As someone who spends more money heating their swimming pool than the total value of the UK state pension, I think it’s safe to say that the Prime Minister might not be as invested in this topic as some others.

“But let’s afford him the opportunity to clear up any confusion.

“Will he commit his party, the Conservative Party, to maintaining the state pension triple lock beyond the next general election – yes or no?”

The Prime Minister replied: “This is the party that introduced the triple lock.

“This is the party that has delivered a £3,000 increase in the state pension since 2010.

“It’s also the party that ensured there are 200,000 fewer pensioners living in poverty today and this winter ensuring that pensioners get an extra £300 alongside their winter fuel payment to support them through the challenging times of inflation.

“So our track record is clear: there is one party in this House that has always stood up for our pensioners and that is the Conservative Party.”

Mr Flynn countered: “I don’t think we heard a yes there.

“You’ll imagine my shock, my utter surprise that we appear to have consensus once again between the Conservative Party and Labour Party on this most important of issues, despite the promises that were made to the people of Scotland in 2014 and despite the clear statements from the likes of Gordon Brown that the only way to protect your pension is to remain within the UK.

“How hollow those words are now.”

He went on to ask Mr Sunak: “Who does he think will scrap the state pension triple lock first – his Government or the Labour Party’s government?”

The PM defended the Government’s support for pensioners, adding: “This is the Government that introduced and remains committed to the triple lock.

“But he does raise a good point, pensioners in Scotland should know the reason that they can rely on the state pension not just today but for years to come is because of the strength of our union and the strength of our United Kingdom Government.”

An 8.5% rise in the full new state pension could take it from around £204 per week to £221, or from around £10,600 to around £11,502 annually.

But a smaller rise of 7.8% would instead take it from around £204 per week to around £220, or around £11,427 annually.

A rise in the basic state pension of 8.5% would take it from around £156 per week to just under £170, or from around £8,122 to £8,814 per year.

But a 7.8% rise would mean an increase in the basic state pension to around £168 per week or around £8,756 per year.

Speaking after PMQs, the Prime Minister’s press secretary told reporters in Westminster: “The Government is committed to the triple lock, you just got the PM’s words in the chamber.

“You wouldn’t expect me to write the manifesto here, but you can take the PM’s words and judge us on our record on that.”

Labour said that the Government was facing a “mess of their own making” after making one-off payments part of deals to end strikes earlier this year.

A spokesman for Labour leader Sir Keir Starmer told reporters: “It has always been the case that one-off payments have been included in the measure of earnings.

“Frankly, one of the reasons why the issue of one-off payments is around at the moment is because of the Government’s total mishandling on the strikes and the public sector one-off payments that there have been clearly shows that the Government did not think about the consequences of the one-off payments they introduced would have in the consideration here.

“But in terms of what they should be doing, then they should be maintaining the triple lock, which is what their promise is. And that means including the figure of wages and one-off payments as earnings.”

The spokesman said that Labour would set out its position on the triple lock closer to the next election.