Liberal Democrat spokesman Lord Oakeshott used parliamentary privilege today to blow a hole in a gag order obtained by Barclays Bank over its tax avoidance scheme.

The documents detailing the schemes, previously leaked to the Lib-Dems, were now available on Wikileaks.org and other websites, he told a Lords debate on tax avoidance.

Barclays had previously obtained a high court injunction banning the Guardian and other papers from disclosing that the documents were publicly available on Wikileaks.org. The gag order, provided by Mr Justice Blake, also forced the Guardian to remove copies of the documents from the paper's own website.

Oakeshott said he believed it was his duty "to tell parliament about Barclays' tax avoidance machine with its aggressive exploitation of tax havens, and to tell the public where they can get chapter and verse, and judge for themselves." He added: "It's a sad day for democracy if a judge sitting in secret can stifle this essential public debate."

The documents leaked to the Lib-Dems "appear to detail systematic tax avoidance on a grand scale by Barclays", he said. They had become front page news as a result "and those documents are widely available on the internet from sites such as Twitter, Wikileaks.org, docstoc.com and gabbr.com".

During the debate, the Treasury minister Lord Myners said he welcomed the steps taken by Barclays' rival, the state-supported RBS, to close down its similar tax avoidance department. He called for co-ordinated international co-operation and a banking code of practice, which the Treasury was now drafting, to make banks follow the spirit of the law and the intentions of parliament. Tax avoidance, he said, "does become a moral issue".