Pakistan's political opposition and news media are criticizing plans for a tough new libel law, saying it will curb freedom of speech and of the press.

Opposition members of Parliament denounced the defamation bill as an unnecessary addition to current libel laws, which will roll back the freedoms enjoyed by Pakistan's news media.

Senior opposition Senator Farahtullah Babar says the law will change slander and libel from civil offenses to criminal ones. "Thereby, a person who is accused of defamation will be sent to jail, rather than being fined," he explaine.

The ruling party says the legislation is needed to stop what it sees as a growing tendency to defame public figures.

Opposition leaders have accused the government of trying to stamp out public dissent. They point to the arrest last year of a senior member of Parliament, Javed Hashmi, over his claim that some top army officers opposed the rule of President Pervez Musharraf.

Mr. Babar says journalists will be the most affected, as any use of off-the-record comments will now open the reporter up to criminal charges. "The press will be scared to continue with its previous practice of independent investigative journalism, and printing stories based on unidentified sources," he said.

Press associations have criticized the bill, despite the government's agreement to remove a clause making editors responsible for their reporters' work.

With the ruling party's strong majority, the bill passed through the lower house Thursday and is expected to be adopted by the upper house in the coming days.

An alliance of opposition religious parties tried to block the bill by demanding that it be forwarded to Pakistan's Council of Islamic Ideology for approval.

But interim Prime Minister Chaudhry Shujaat Hussain, a strong supporter of the proposed law, turned down the motion, saying Islam clearly opposes slander.

Senator Babar says the opposition's best chance now lies in mounting a challenge in the Supreme Court, once the law passes.