A senior civil servant has said he was wrong to claim the UK took a "political decision" not to join an EU scheme to source medical equipment.
The Foreign Office's Sir Simon McDonald told MPs that ministers were briefed on "what was on offer" but said "no".
But he later retracted his comments, saying he had "wrongly" told MPs that ministers been briefed on the scheme.
He said the UK did not receive an invitation to join the scheme because of "communication problems".
Ministers have insisted they did not receive emails alerting them to the deadline for joining the EU procurement scheme for gowns, ventilators and testing kits in March.
And Health Secretary Matt Hancock denied that politics had been involved in the decision and said he had signed-off on joining efforts to procure more equipment.
However, a European Commission spokeswoman suggested the UK was aware of the tender programmes and had chosen not to get involved after its departure from the bloc on 31 January.
Last month the government was criticised for not taking part in an EU plan to bulk buy medical equipment, including potentially life-saving ventilators, that could be used to tackle the coronavirus.
At the time, Downing Street said the UK was making its own arrangements because it was no longer in the EU.
Ministers denied claims that anti-EU sentiment had played a part in the decision.
Downing Street then issued a statement saying the UK had been invited to take part but officials did not see the email because of a "communication confusion".
Asked why the decision was taken not to join the scheme, Sir Simon - who is permanent secretary at the Foreign Office - told the Foreign Affairs Committee that it was a deliberate move by ministers.
"We left the European Union on 31 January," he said.
Pushed further, he added: "All I can say is that it is a matter of fact that we have not taken part. It was a political decision... and the decision is no."
But five hours later, he released a letter to the chair of the committee, Conservative MP Tom Tugendhat, saying he had been wrong in what he said.
"Due to a misunderstanding, I inadvertently and wrongly told the committee that ministers were briefed on the joint EU procurement scheme and took a political decision not to take part in it," he wrote.
"That is incorrect. Ministers were not briefed by our mission in Brussels about the scheme and a political decision was not take on whether or not to participate."
He added that "the facts of the situation are as previously set out" and the UK missed the opportunity to take part "owing to an initial communication problem".
The EU started to coordinate the process of purchasing personal protective equipment (PPE), testing kits and ventilators at the end of February. The joined effort helps to reduce costs when negotiating with manufacturers.
The first scheme, to purchase masks, was launched on 28 February.
For ventilators, the procurement procedure was launched on 17 March, with the closing date of 26 March by which countries had to say whether they would like to participate and how much they would need.
A further scheme for PPE was launched on 17 March and one for testing kits on 19 March.
However, so far no PPE, ventilators or testing kits have been delivered through the schemes.
Sir Simon had earlier been contradicted by ministers, with Mr Hancock saying he had spoken to the Foreign Secretary Dominic Raab, and as far as he knew there had been no political decision not to participate.
Speaking at the daily coronavirus briefing, he revealed that he had now accepted an invitation from the EU to join that particular scheme on an "associate" basis but said it had not yet delivered a single item of medical equipment.
"When we did receive an invitation in the Department of Health… it was put up to me... and we joined and we are now members of that scheme, but as far as we know that scheme hasn't yet delivered a single item of PPE."
The decision not to join earlier had had "zero" impact on the UK's current supplies, he suggested.
Speaking before Sir Simon issued his clarification, Labour's shadow health secretary Jonathan Ashworth said ministers themselves needed to explain what had happened.
"We were told the government missed an email invitation to join the EU procurement scheme. Then we were told the decision not to take part was a political decision.
"Now we are told that the government did sign up to the scheme," he said.
The BBC's political editor Laura Kuenssberg said the row reflected the intense pressure on the government over its record on key equipment and whether its rhetoric about doing all it could was backed by the reality.
And she added later:
McDonald says that there was a 'misunderstanding' and ministers weren't briefed by UK mission in Brussels - but doesn't say whether ministers were briefed on it by anyone else— Laura Kuenssberg (@bbclaurak) April 21, 2020