A week after the death of Russian spy Alexander Litvinenko from suspected radiation poisoning, the Muswell Hill road in which he lived remained sealed off in two places after traces of radiation were discovered.

Polonium-210 has been found at the 43-year-old's home in Osier Crescent, off Coppetts Road, where he lived with his wife Marina and their 12-year-old son.

Across the road, a car - believed to be a silver Mercedes belonging to a Russian-speaking neighbour who knew Mr Litvinenko well - had also been cordoned off yesterday with a white and blue tarpaulin placed over it.

Mr Litvinenko's wife and son have undergone radiation tests but there is no official word on the results. Neither have been seen at the house since Mr Litvinenko died last Thursday.

Most neighbours knew nothing about Mr Litvinenko's past. Their shock at discovering that a former KGB spy lived in their street turned into panic when they learned that radiation had been discovered at his home.

One neighbour said: "Obviously I was petrified at first, but we phoned the NHS helpline and they said there was no risk of contamination. Because I have a baby I was obviously worried."

Lindsey Merdick, who also lives close by, said: "We were all terrified."

Nick Priest, professor of radiobiology at Middlesex University and an expert on the toxicity of polonium-210, said Mr Litvinenko's family, friends and neighbours were in no danger.

He said: "It's highly unlikely anybody will be exposed to significant levels of radiation, with a few exceptions, potentially the person who gave it to him; and the people that prepared it.

"Anybody else would be exposed to much lower levels."

Hornsey and Wood Green MP Lynne Featherstone described the nature of Mr Litvinenko's death as horrific'.

She has demanded assurances from Home Secretary John Reid that Mr Litvinenko's death be investigated without fear or favour and that diplomatic sensitivities with Russia will not prevent the full, fair and free findings of that investigation.

Mr Litvinenko's family and friends have accused the Russian Government of his murder.