The news came after The Daily Telegraph tracked Mr Koussa to a 17th floor penthouse at the Four Seasons hotel in Doha, the capital of Qatar.
The former Libyan intelligence chief and foreign minister is thought to have been living there for several weeks, since being allowed to leave Britain after he defected this year. It is understood his hotel bills are being met by Qatar.
News of Mr Koussa’s whereabouts came as the International Criminal Court yesterday issued arrest warrants for Col Muammar Gaddafi, his son Saif al–Islam and the intelligence chief Abdullah al–Senussi.
David Cameron’s official spokesman said the Government wanted to see Mr Koussa help rebels in Libya from his base in Doha.
He said: “It is not for us to give a commentary on what Moussa Koussa is doing. We want to see him play his part in opposing the Libyan regime.”
Asked if it was possible to “do that from a five–star hotel in Doha”, he said: “I am not going to get into a lot of commentary on what Moussa Koussa is doing – he is a private individual.”
The spokesman added: “We have also been clear that he will not be given any immunity from prosecution in this country.”
Mr Koussa had “already been interviewed by Dumfries and Galloway police” over the Lockerbie bombing, he said.
In Parliament, a Conservative MP said he would be asking what level of financial support, if any, Britain had given Mr Koussa since he came to the UK after defecting from Col Gaddafi’s regime.
Robert Halfon, MP for Harlow, said: “Allegedly this man has blood on his hands, and I hope very much that the British taxpayers are not subsidising him in any way.”
Mr Koussa defected to Britain at the end of March but left for Qatar shortly afterwards to take part in a “Gulf contact group” meeting of countries hoping to resolve the Libya crisis.
He was expected to return to Britain, where he is facing calls for his prosecution over accusations ranging from the Lockerbie bombing to supplying arms to the IRA, but is currently showing no signs of doing so.