A four-nation coronavirus recovery summit has been postponed because the Scottish and Welsh governments need “more time to prepare”, Downing Street has said.

Nicola Sturgeon and Mark Drakeford had written to the Prime Minister calling for the talks planned for Thursday to be a “meaningful discussion with substantive outcomes”.

The first ministers of Scotland and Wales asked Boris Johnson for more clarity and substance around the proposals.

Downing Street said Thursday’s summit has been cancelled but will be rescheduled “as soon as possible”, though no date has been set.

The Prime Minister’s official spokesman said: “We had scheduled for this meeting to happen tomorrow.

“As the PM set out, we need to overcome the significant challenges of the Covid recovery with the same spirit of unity and co-operation that we’ve seen during the fight against the pandemic.

“It is disappointing that the Scottish Government and the Welsh Government would prefer to delay this meeting so they have more time to prepare, especially given the scale of that challenge, but we remain committed to that spirit of co-operation.”

In the letter, copied to Northern Ireland First and deputy First Ministers Arlene Foster and Michelle O’Neill, Ms Sturgeon and Mr Drakeford criticised Mr Johnson’s office for sending “a very rough proposed agenda” with key issues in the discussions seemingly yet to be agreed.

They also made a case for “further discussion” to take place ahead of the summit, which would see such an event delayed but still held “perhaps as early as next week”.

News of postponement of the talks comes as Dominic Cummings told MPs that Mr Johnson initially believed coronavirus was like “swine flu” and he claimed people died unnecessarily because of Government failings during the pandemic.

Mr Cummings, the PM’s former adviser who left Downing Street last year after a behind-the-scenes power struggle, told MPs on Wednesday: “The truth is that senior ministers, senior officials, senior advisers like me, fell disastrously short of the standards that the public has a right to expect of its Government in a crisis like this.

“When the public needed us most, the Government failed.

“I would like to say to all the families of those who died unnecessarily how sorry I am for the mistakes that were made and for my own mistakes at that.”

While Mr Cummings was giving evidence, Mr Johnson was facing Prime Minister’s Questions. He said: “None of the decisions have been easy, to go into a lockdown is a traumatic thing for a country. We have at every stage tried to minimise loss of life.”

A spokesman for the Scottish First Minister said: “The summit would be going ahead tomorrow if the UK Government were remotely prepared for it.

“As we and the Welsh Government made clear in our letter to the Prime Minister, what they had suggested was simply a PR exercise without proper substance.

“We have asked for a detailed agenda to be prepared for a serious meeting, which is what this subject deserves.”