Mario Scaramella is "well" and preliminary tests have shown he is not showing signs of illness, University College Hospital in London said.

The Italian was one of the last people to have met ex-spy Litvinenko before his death. Officials had previously said he tested positive for traces of polonium-210.

Scaramella's condition is said to have remained the same as it had been on Friday. Litvinenko's wife Marina is also said to have been "very slightly contaminated" but is not ill.

Health officials stressed the public were in no way at risk, despite two people connected with Litvinenko testing positive for radiation exposure.

Easyjet has confirmed that Scaramella flew on flight 3506 from Naples to Stansted on 31 October and also on flight 3505 from Stansted to Naples on 3 November.

The Health Protection Agency (HPA) said it had no "public health concerns" about those flights.

It also said all three British Airways planes at the centre of the polonium-210 scare have been given the all-clear and are able to return to service.

The airline has been trying to contact 33,000 passengers from 221 flights after traces of the radioactive material were found on two if its planes.

Yesterday the Russian transport ministry's press service said traces of radiation have been found on a Finnish plane in Moscow that had flown from Berlin via Helsinki.

HPA chief executive Pat Troop said: "People should be reassured that we're not allowing anything to be open if we are not content about it." The agency said the levels of polonium-210 discovered in Mrs Litvinenko were "not significant enough to result in any illness in the short term and any increased risk in the long term was likely to be very small".

Professor Anthony Glees, from the Centre for Intelligence and Security Studies at Brunel University, told BBC Five Live that MI5 were taking what had happened very seriously. He said "the fact that you could get it onto planes despite all the security measures that we all go through every time we fly, is causing very serious disquiet.

Meanwhile, it has been confirmed that experts from the Sellafield nuclear plant in Cumbria are involved in the investigation into the Litvinenko poisoning.

Several staff members have been sent to London at the request of the HPA, and more are set to go on Monday, a spokeswoman for the British Nuclear Group said.