A report on Britain's extradition treaty with the United States offers guidelines only about whether suspects such as Gary McKinnon could be tried in the UK, the Attorney General has told MPs.

Dominic Grieve said the Government was forming a response to the Baker Report and would consider issues such as a "forum bar" rule which could see suspects tried here if a judge believes it will better serve justice.

Livingston Labour MP Graeme Morrice said: "What consideration are you giving to implementing a forum bar to give more discretion to judges to decide where it is in the interests of justice for cases to be tried in the UK, such as in the case of Gary McKinnon, where the offence was committed in the UK and it is difficult for the defence and witnesses to go to a foreign jurisdiction?"

Mr Grieve told the Commons: "That is touched on in Lord Justice Scott Baker's report and it is one of the matters which will have to be taken into account when the Government responds to it.

"His proposals are rather more in the nature of guidelines rather than the implementation of the forum bar itself. That is one of the matters the Government is going to have to consider."

Former Lib Dem leader Sir Menzies Campbell said he disagreed with the report's conclusions on the standard of proof required to initiate an extradition on either side of the Atlantic and called for reassurance from the Attorney General.

Sir Menzies said: "In determining these matters, will proper account be taken of the principle of reciprocity and will you ensure British citizens are not at a constitutional disadvantage in comparison to their American counterparts?"

Mr Grieve replied: "That was one of the reasons we asked for the matter to be looked into by Lord Justice Scott Baker. We're going to have to take account of what he has put forward and I hope you will make a contribution."

Isabella Sankey, Liberty's director of policy said: "It's heartening to hear MPs speaking against unfair extradition. The majority of the last parliament - including all those now in the cabinet - voted for a forum bar - and a Liberty poll last year revealed similar overwhelming support in the Commons.

"The Attorney General has rightly clarified that the Scott Baker report is merely the beginning of a debate on which Parliament must now decide."