Igor Sutyagin, the Russian arms control researcher brought to Britain as part of a spy swap between the US and Russia, is staying at a hotel in a small town near London, his mother has told the Guardian.

Svetlana Sutyagina said her son had made a brief call to his wife, Irina Manannikova, yesterday afternoon after being flown into RAF Brize Norton in Oxfordshire from Moscow the previous day.

"He managed to get a phone card from somewhere and make a short call to his wife," said Sutyagina, speaking from her home in Obninsk, near Moscow. "He said he was staying in a hotel in a small town near London. He may have told Irina the town but she was in such a state of anxiety that she didn't remember the name. We were all so worried that we had not heard from him."

Sutyagina added: "Igor is still in his prison robe, he has no other clothes and he's got practically no money. He did not have time to say much before the phone card ran out. He couldn't give us a number to call him back. It appears his movements are restricted. He has his Russian passport with him but he has no British visa in it. It would be unwise for him to go out.

"It's Igor's understanding that nothing is happening because it's the weekend and tomorrow things will become clearer, and the paperwork will be sorted out. He said he feels unsettled but he expects to get used to England little by little. He still hasn't decided if he wants to stay in Britain.

"Everything is so unclear and he needs some time to consider his options. We have given him contacts of scientists and others in London who may be able to help. But he could yet return to Russia. As far as we know, there is nothing to stop him doing that."

Meanwhile, Sutyagin's lawyer, Anna Stavitskaya, told Interfax that his "scientist friends" called from the UK and said they were ready to put him up. "They live in London. They are ready to provide him with everything he needs."

Sutyagin, and three other Russians convicted of spying for the west were exchanged on Friday in Vienna for 10 Russian agents deported from the US, who arrived in Russia to a tepid reception.

The four expelled by Russia were flown to Britain where Sutyagin and Sergei Skripal, a former colonel in the Russian military intelligence, got off. Skripal, who was found guilty of passing state secrets to Britain, is in the same hotel, as Sutyagin. The plane went on to the US with the other two agents.

All four were pardoned by President Dmitry Medvedev before being expelled, raising the possibility they could be allowed to return to Russia.

Sutyagin was arrested in 1999 and convicted in 2004 of spying. Authorities said he provided information about nuclear submarines to a British company alleged to be a CIA front. Sutyagin maintained his innocence, saying all the information he provided was available from open sources.

Sutyagin, who had been imprisoned near Arkhangelsk, in Russia's far north-west, met Russian and US officials on Monday and was told he would be sent to Britain in the swap.

Nothing has been heard of the 10 sleeper agents who flew into Domodedovo airport from the US on Friday night and immediately driven away in a convoy of SUVs and small buses. Russian media reported that Anna Chapman, the businesswoman who lived in New York, called her sister briefly to say: "Everything is OK, we've landed."

Chapman's mother was seen leaving her home in a Moscow suburb about an hour and a half before her daughter's plane landed. She refused to talk to reporters.