The House of Lords is set to make concessions to those who expressed alarm about measures to block Web sites in the government's Digital Economy Bill aimed at tackling piracy.

Last week amendment 120A was passed by opposition peers in the Lords in response to concerns about the original measures in Clause 17, which would have given the government substantial powers to amend the law to deal with any future piracy threat.

However, the new amendment got an angry response from Internet companies. The measures would allow the High Court to grant an injunction requiring ISPs to block Web sites with a "substantial proportion" of copyright-infringing content.

Companies including Google, Yahoo and Facebook joined the U.K.'s largest Internet Service Providers, as well as consumer rights campaigners and academics, in writing a joint letter to the Financial Times March 10 saying that Clause 120A could "threaten freedom of speech and the open Internet."

The Liberal Democrats will publish changes to the amendment today (March 12) according to the Financial Times, and the Conservative opposition has indicated it will support the revised proposals. The revised measures would enable a judge to order copyright owners to pay legal costs and compensation for asking a service provider to block a site; content owners would also have to inform owners of sites accused of infringement and list the works in question, before requesting that the site be blocked.

Site owners or other "aggrieved" people would be able to appeal against a block on the site.

Conservative shadow culture secretary Jeremy Hunt told the FT that Clause 120A had been "trying to do the right thing" but needed revision to avoid "any unintended consequences." Hunt said his party did not want ISPs to "agree to block hundreds and hundreds of Web sites just because that is the easiest route."

ISPs would have been required to pay legal costs of challenging a court order under the amendment passed March 3. The Internet Service Providers Association (ISPA) said it was "outraged" after that was passed, and argued that Clause 120A introduced a "bias in favor" of rights holders and would limit the court's discretion to judge each case on its merits.

It has also emerged that the unpopular amendment is almost identical to a draft written by the U.K. record labels' trade body the BPI. Liberal Democrat peer Lord Clement-Jones appears to have incorporated that into his amendment 120A.

The revised proposals will be voted on March 15 at the bill's third reading in the Lords.