Claire Doole: "It looks as if the net is closing in"

Mr Tomlinson, who has been living in Geneva since October last year, told the BBC he plans to fly to any country that will accept him. His solicitor confirmed that he was detained briefly by Swiss police and asked to go.

The former spy has already been barred from the United States, France, New Zealand and the United Kingdom.

Mr Tomlinson, who was dismissed by MI6 in 1995, denies government allegations of posting the names on the Internet last month. However, the Swiss authorities have opened an investigation into the allegations.

Internet threats

After being dismissed, he went to live in Spain and, in an attempt to get back at his former employer, wrote articles for the British press.

This, alongside his threats to expose MI6 in detail on the Internet, saw Mr Tomlinson arrested on his return to the UK. In 1997 he became the first MI6 agent to be tried under the Official Secrets Act since George Blake in 1961.

He pleaded guilty and served six months in a British prison.

Claire Doole: "There are few places left to run to"

After the list of agents became known to security forces, frantic efforts were made to remove it.

But several "mirror" sites appeared on the Web, recording thousands of hits.

The Swiss have now asked him to leave, saying his presence is "undesirable". If he returned to the UK he would be re-arrested under the Official Secrets Act.