A gagging order that barred a national newspaper reporting details of a Parliamentary question was lifted today after widespread condemnation from MPs and an overwhelming internet campaign.

The Guardian newspaper was blocked from publishing the contents of the question which involved the oil company Trafigura.

The ban extended to the name of the MP who tabled it, which minister was due to answer it or why the order was in place.

But lawyers who had obtained the order, the media law firm Carter Ruck, withdraw their opposition to reporting of the question after it was widely published on micro-blogging site Twitter, by political bloggers and amid an avalanche of complaints.

MPs had earlier called for an emergency Commons debate amid outrage at Westminster over what was seen as a threat to Parliamentary privilege.

The parliamentary question, tabled by Paul Farrelly, MP, detailed injunctions or gagging orders including one obtained by Trafigura, which recently settled a claim brought by 30,000 Africans over toxic waste dumped in the Ivory Coast.

Mr Farrelly has asked Jack Straw, the Justice Secretary: “What assessment he has made of the effectiveness of legislation to protect (a) whistleblowers and (b) press freedom following the injunctions obtained in the High Court by (i) Barclays and Freshfields solicitors on 19 March 2009 on the publication of internal Barclays reports documenting alleged tax avoidance schemes and (ii) Trafigura and Carter Ruck solicitors on 11 September 2009 on the publication of the Minton report on the alleged dumping of toxic waste in the Ivory Coast, commissioned by Trafigura.”

Thousands of Twitter users joined in the campaign, including Stephen Fry, and the terms "Carter-Ruck" and "Trafigura" went straight to the top of the site's "trending topics" list.

The Liberal Democrats joined the campaign. Nick Clegg, the party leader, tweeted: "Very interested concerned about this #trafigura / Guardian story the @LibDems are planning to take action on this."

Within hours of the question being published online, the gagging order had been dropped.

The Guardian was due to go to court to challenge the order but the law firm then dropped its claim that to report Parliament would be in contempt of court.

Its editor, Alan Rusbridger, hailed a “great victory for free speech” and said the lawyers had “caved in”.

Mr Rusbridger, who had condemned the restriction as “Kafka-esque”, broke the news that it had been lifted on Twitter, which had been inundated with posts condemning the reporting restriction.

“Victory! CarterRuck caves-in. No Guardian court hearing. Media can now report Paul Farrelly’s PQ about Trafigura,” Mr Rusbridger wrote.

“Thanks to Twitter/all tweeters for fantastic support over past 16 hours! Great victory for free speech,” he wrote - hours after saying he was seeking a court hearing to overturn the ban.

Professor Gary Slapper, director of the Open University law programme, said: “Parliament, already tainted by the hubbub of MPs trying to excuse their endemic financial misconduct, is now under a more sinister spectre.”

The order, he added, had “violated a most fundamental and cherished part of the British constitution; that Parliament is sovereign and cannot be controlled by private interests operating through the courts.”

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