A rise in national insurance to help pay for social care has not been ruled out in the long term but is not expected in plans due this year, a Government minister has said.

Reports earlier this week claimed Boris Johnson was considering plans to raise national insurance payments by one percentage point for employers and employees to raise £10 billion a year to help support the ageing population.

Downing Street did not deny the reports on Tuesday, as reform plans were promised before the end of the year.

On Wednesday, No 10 said “no decisions” had been made.

On Thursday, Business Secretary Kwasi Kwateng was asked if there could be no national insurance hike.

He told Sky News: “That’s what it says in the manifesto, I don’t see how we could increase national insurance, but you know things have been very flexible over the last 18 months, we’ve lived through an unprecedented time, we’ve been spending huge amounts of money that we never thought was possible and it’s up to the Chancellor and the Treasury, and the wider Government, to decide a budget.”

He said he believes a social care plan will come “by the autumn”.

“I don’t think we’ll put up national insurance in that specific…” he said.

The plan is not expected before the autumn, with the Commons set to rise for its summer break following Thursday’s business.

There had been widespread expectation that a plan would be put forward before the summer, but the three main players who would be involved in the decision – the Prime Minister, Chancellor and Health Secretary – are all self-isolating.

Any rise in national insurance has faced criticism as it would be expected that it disproportionately hit younger people.

A spokesman for Boris Johnson said: “The Prime Minister has been clear that we will set out details later this year and that no decisions have been made.

“But we are and remain committed to setting out proposals in this area this year.”

Asked whether Mr Kwarteng was incorrect to suggest a national insurance hike was not part of the thinking on social care, the spokesman replied: “I’m here to speak on behalf of the Prime Minister and I’m pointing you back to comments the Prime Minister has made.”