David Cameron raised the prospect today that computer hacker Gary McKinnon could serve some of any US-imposed sentence in a British jail after raising the issue with US president Barack Obama at the White House.
He said it was "one potential outcome" of senior-level talks between Britain and the US over the fate of Mr McKinnon, who broke into top secret US military computers.
The Prime Minister told BBC Radio 5 Live that the Government had been working with the US ambassador on options "where perhaps some of the (sentence) if there is a prison sentence - is served in a British prison".
"That is one potential outcome and I'll be working very hard to make sure that these things are discussed between the two governments and if we can reach a settlement then all to the good.
"I don't want to make a prediction because there are many difficult issues that have to be worked through."
Both Mr Cameron and Deputy Prime Minister Nick Clegg have publicly condemned plans to extradite Mr McKinnon to the US - where he faces up to 60 years in jail.
Last year Mr Cameron said that if Mr McKinnon, 43, had questions to answer there was "a clear argument to be made that he should answer them in a British court".
Speaking at a White House press conference alongside President Obama yesterday, Mr Cameron said: "Clearly there is a discussion going on between the British and the Americans about this but I don't want to prejudice those discussions,
"We completely understand that Gary McKinnon stands accused of a very important and significant crime in terms of hacking into vital databases and nobody denies that is an important crime that has to be considered.
"I have had conversations with the US ambassador as well as raising it today with the president about this issue, and I hope a way through can be found."
President Obama said he had spoken with Mr Cameron about the "increasing challenge" faced by the internet and the need for greater co-operation on cyber security.
He added: "One of the traditions we have is that the president doesn't get involved in decisions around prosecutions, extradition matters.
"So what I expect is my team will follow the law, but they will also co-ordinate closely with what we have just stated is an ally that is unparalleled in terms of our co-operative relationship.
"I trust that this will get resolved in a way that underscores the seriousness of the issue, but also underscores the fact that we work together, we can find an appropriate solution."
Authorities in the US want Mr McKinnon to stand trial for hacking into top secret military computers.
Mr McKinnon, who suffers from Asperger's syndrome and comes from Wood Green, north London, says he was looking for evidence of UFOs.
Mr McKinnon's mother Janis Sharp said she was delighted her son's case had been raised by the Prime Minister.
She told GMTV: "It was amazing that we've now got someone brave enough in government to actually stand up for British citizens and to raise it with Obama."
She added that her son was "in shock" after hearing his case had been discussed and said: "For him to know that he can stay here and be tried here would be just such an amazing relief."
Speaking to GMTV, Mr Cameron said the McKinnon case was "very difficult".
He added: "We can't deny the fact of what Gary McKinnon is accused of doing.
"We are going to review the extradition treaty, we are looking at that, specifically to ask whether it is balanced and fair between the two countries. It should be, and that will be a proper process that will be looked at and we will announce the conclusions when we have them."
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