Sir Michael Graydon, the head of the RAF, wrote to Kenneth Clarke, Chancellor of the Exchequer, and Michael Portillo, the Chief Secretary, 'regretting' that his speech on Monday night had been interpreted as a personal attack on them.
Sir Michael's letters of apology came after he had been summoned yesterday by Malcolm Rifkind, Secretary of State for Defence, and told that he had significantly exceeded his remit as a public servant by launching his outspoken attack.
Mr Rifkind was said in Whitehall last night to have been as 'furious' as the Treasury ministers. It was also said in Whitehall that he had not cleared Sir Michael's speech, though this was 'not unusual'.
Mr Rifkind's temper had not been improved by a protest telephone call he had received from Mr Portillo on Monday night shortly after television news bulletins had carried details of Sir Michael's speech to the Air League.
In the speech Sir Michael suggested a campaign of denigration had been mounted in advance of planned public expenditure cuts, and added: 'We know who has instigated it.'
Apologising for the 'embarrassment' caused by the speech and 'the inference drawn thereafter by the media', Sir Michael said: 'I have no evidence that any Treasury minister has instigated a press campaign against the RAF or the other services. My sole intention was to refute some of the more serious misrepresentations in the press.'
Sir Michael's speech follows a semi-public campaign against defence cuts during which Defence Department sources continued to insist - while making clear their opposition to Treasury plans - that it was the Treasury which had leaked original information about proposed cuts. In an emphatic denial of that charge, Mr Portillo declared last night: 'Having read the speech by Air Chief Marshal Sir Michael Graydon I have made inquiries within the Treasury. I am confident that, in accordance with instructions from the Chancellor and me, Treasury officials have not offered briefings to the press on the defence programme.'
Despite acceptance by some senior MPs that the Treasury had less motive for leaking information about their plans than the MoD, others rode to the support of Sir Michael last night. Sir Nicholas Fairbairn, a senior member of the Commons all-party Defence Committee, said: 'Sir Michael has been leaned on. In other words we have a defence force which is not only gravely and I think woundingly diminished, but we now have a bunch of blackguards who can lean on a fellow for saying so and make him splutter his apologies.'
Menzies Campbell, the Liberal Democrats' defence spokesman, said: 'Sir Michael Graydon may have been prevailed upon to withdraw his criticism. But anyone who followed the course of the argument about defence in the last few weeks will be more than suspicious that Sir Michael had it just about right.'