Sources close to the Prime Minister said Mr Major was annoyed that the stupidity of two Tory MPs had unsettled his efforts to pull the party together before the long summer recess.
The Government is hoping the inquiry will clear the air over the affair, but it fears it will rekindle the Labour spring offensive over 'Tory sleaze'. One party source said: 'If the Sunday Times had been really clever, it would have waited a fortnight and done it after the reshuffle. Then we would have had this row rumbling right through the summer.'
MPs were split down party lines over the targets for the investigation by a Committee of Privileges.
Tory MPs rounded on the Sunday Times for alleged 'entrapment' of Graham Riddick, MP for Colne Valley, and David Tredinnick, MP for Bosworth, with the offer of pounds 1,000 to table Commons questions.
But Labour MPs wanted the inquiry to highlight the extent to which Tory MPs are engaged in private consultancies, directorships and as paid advisers.
Nick Brown, Labour MP for Newcastle upon Tyne East, said he will today table the motion for the debate to satisfy both sides. It will focus on three issues: the Tory MPs named by the Sunday Times; the tactics used by the newspaper; and the wider question of members' interests.
'I take a puritanical view . . . I don't think you should have any outside remuneration,' he said.
Conservative Party leaders said they wanted tighter rules to be laid down, making it clear what MPs must not do in accepting payment.
The two MPs had little sympathy from colleagues. 'The word chump springs to mind,' said one leading Tory party source.
'It's all a bit tacky,' said a Maastricht rebel. 'It won't do us any good.'
But another Tory backbencher said: 'I put down questions for the whisky industry. I declare it. Everybody knows it. I can't see what's wrong in that. It's the only way you can get information out of the Government.'
David Tredinnick and Graham Riddick, the two MPs who were reported to have had cheques for pounds 1,000 sent to their homes, are expected to use today's debate to defend themselves.
The prompted question, tabled by Mr Tredinnick, mentioning Sigthin, a non-existent drug, yesterday appeared on the Commons order paper. Labour MPs pointed out he had tabled another question yesterday. It was about comfrey, a herbal remedy for illnesses, including a sick stomach.