Tory former Minister Alan Clark last night urged MPs not to turn media magnate Rupert Murdoch into their latest ''villain'' - because with patience he might disappear like other great press barons of the past.

The Kensington and Chelsea MP complained that everybody in politics was obsessed with Mr Murdoch, head of News International which owns the Times, the Sunday Times, the Sun and BSkyB.

However, in the second reading debate on the Competition Bill, Mr Clark took a sideswipe at the press, describing journalists as ''victims often of their own squalid and unfulfilling lifestyle - of their dependence on alcohol and narcotics''.

They ''should be objects of sympathy for us, we should commiserate with them'', he told MPs.

Mr Clark condemned the Bill and a Lords amendment aimed at outlawing newspaper predatory pricing as ''absurd, inconsistent and contradictory'', adding: ''In fact, it is little more than censorship by the back door.''

Mr Clark said it was extraordinary ''the House and practically everybody in politics is obsessed'' by Mr Murdoch.

Mr Clark said he did not understand why MPs were so upset when newspapers undercut prices. He reminded Labour MPs that in Opposition they had been against ''fat cats and privatised industry'' for putting up margins and overcharging.

The Government moved last night to head off a potentially damaging back-bench revolt over newspaper ''predatory pricing''.

A Tory bid to block the second reading of the Competition Bill was defeated by 314 votes to 169, Government majority 145, after President of the Board of Trade Margaret Beckett assured would-be rebels the measure strengthened anti-competitive law.

Mrs Beckett rejected as unworkable and unnecessary a Liberal Democrat amendment, on which the Government was defeated in the Lords, which would outlaw the cut-price campaigns by newspapers.

Confirming the Government would act to overturn the defeat at the Bill's committee stage, she stressed the Government's legislation would help combat predatory pricing and other abuses of a dominant market position.

With Conservative concerns centering on the allegedly damaging effect on small pharmacies of ending retail price maintenance on over-the-counter medicine, Shadow Trade President John Redwood branded the Bill a ''muddle and a ragbag''.

Mr Redwood said the Opposition saw no need for new legislation on the newspaper industry and would not be supporting the Lords amendment, since it was not needed to make predatory pricing an offence.

However Parliamentary Labour Party chairman Clive Soley, an outspoken critic of the pricing policies of News International, said the legislation would not on its own tackle monopolies in the newspaper industry.

Earlier, Mr Clark had claimed that some jails ''actually encourage'' drug-taking to keep inmates happy. He told the Commons at question time that the ''easiest way'' to prevent a prison riot was to allow drugs to circulate.

However Junior Home Office Minister George Howarth rejected his claims and accused him of peddling ''stupid arguments'' in the House.