LONDON, England (CNN) -- The British government will push for a computer hacker who broke into Pentagon and NASA computers to serve his jail time in the United Kingdom if a United States court sentences him to jail, a top politician said Sunday.
Briton Gary McKinnon is accused of carrying out the biggest ever U.S. military hacking operation.
"We'll seek for him to serve any prison sentence, if he is sentenced to prison, back in this country," said Harriet Harman, the deputy leader of Britain's governing Labour Party.
Hacker Gary McKinnon, a British citizen, has admitted breaking the law and intentionally gaining unauthorized access to U.S. government computers.
The U.S. wants him extradited to face trial there, while he has been fighting to be tried in Britain.
He bases his case partly on the fact that he has Asperger syndrome, a type of autism.
He lost an appeal at the High Court on Friday, bringing him a step closer to extradition.
The case has sparked widespread anger in Britain from people who think he should not be sent abroad for trial.
But Harman said Sunday the legal system was working as it should.
"The director of public prosecutions says because the witness are in America, because the damage that was alleged to have been done was in America, because the evidence is in America, that is the appropriate place to put him on trial," she said on the BBC's "Andrew Marr Show."
She said Washington had promised the British government McKinnon would be properly cared for.
"There certainly have been assurances sought and given that ... if and when he is taken over to America, his health needs will be attended to," Harman said.
She said it was right that the government not intervene.
"It shouldn't be politicians who make judgments about the criminal justice system," said Harman, a former human-rights lawyer. "We don't find people guilty or not guilty. That's not the job of ministers."
McKinnon's mother, Janis Sharp, promised to appeal Friday's decision to Britain's new Supreme Court, which will come into existence in the fall.
The U.S. government says McKinnon carried out the biggest military computer hacking of all time, accessing 97 computers from his home in London for a year starting in March 2001, and costing the government about $1 million.
McKinnon, currently free on bail in England, has said he was simply doing research to find out whether the U.S. government was covering up the existence of UFOs.
McKinnon's lawyer, Karen Todner, complained that her client would be extradited according to a treaty intended for terrorists.
"Why aren't they stopping the extradition of a man who is clearly vulnerable and who on the accepted evidence suffers from Asperger's?" she said in a statement. "Gary is clearly someone who is not equipped to deal with the American penal system and there is clear evidence that he will suffer a severe mental breakdown if extradited."
U.S. federal prosecutors accuse McKinnon of breaking into military, NASA and civilian networks, and accessing computers at the Pentagon; Fort Benning, Georgia; Fort Meade, Maryland; the Earle Naval Weapons Station in Colts Neck, New Jersey; and the Johnson Space Center in Houston, Texas, among others.
In one instance, McKinnon allegedly crashed computers belonging to the Military District of Washington.
McKinnon is thought to have acted alone, with no known connection to any terrorist organization, said Paul McNulty, the former U.S. attorney for the Eastern District of Virginia.
A U.S. federal grand jury indicted McKinnon on seven counts of computer fraud and related activity. If convicted, he would face a maximum of 10 years in prison on each count and a $250,000 fine.
McKinnon has previously said it was easy for him to access the secret files.
"I did occasionally leave messages in system administrators' machines saying, 'This is ridiculous,'" McKinnon has said. "(I left) some political diatribes as well, but also a pointer to say, you know, this is ridiculous."