Attempts to water down freedom of information laws will be fought "every inch of the way", Lewes MP Norman Baker vowed today.

The Liberal Democrat spoke after supporters of a private members' Bill which would exempt Parliament from the Freedom of Information Act postponed debate on the measure until next month.

Mr Baker said the move to delay the Commons clash, which had been scheduled to take place yesterday morning, was an attempt to secure extra time for discussion and increase its chances of becoming law.

He said he and other opponents of the Bill had cleared their diaries and would be ready for the next Parliamentary showdown on May 18.

The MP, who helped thwart the Bill's passage the last time it came before the Commons by speaking for more than two hours, said: "Far from throwing in the towel it seems that David Maclean (the Tory MP behind the Bill) is redoubling efforts to get his disgraceful Bill through.

"He knew that he would have little time so by choosing May 18 he is clearly hoping to have yet another full day on this wretched Bill.

"The efforts to which Mr Maclean is going to push his Bill through is astonishing."

Time for debate on Mr Maclean's move would have been limited today because it was the second item on the Commons order paper behind another backbench Bill on building societies.

Mr Baker said: "I can tell Mr Maclean that I have cleared Friday May 18 from my diary and have no doubt that many colleagues will be doing the same thing.

"We will fight this every inch of the way."

Mr Maclean's Freedom of Information (Amendment) Bill would exempt both the Commons and the Lords, as well as MPs' correspondence, from the provisions of the Freedom of Information Act.

Supporters say it is needed to protect the confidentiality of MPs' correspondence with constituents, but critics say the real aim is to block embarrassing disclosures about MPs' expenses and allowances.

The Government has insisted it has no position on the Bill, but its lack of opposition to date has been interpreted as tacit support.

Several ministers - including Tessa Jowell, Tony McNulty, Andy Burnham, Ian Pearson and John Healey - voted for the legislation earlier this month, when Mr Baker and others talked for several hours to prevent the Bill becoming law.