A Sussex hotel has been sealed off after it was revealed a man at the centre of the Litvinenko poison plot was a guest.

Italian academic Mario Scaramella, a contact of dead ex-spy Alexander Litvinenko, has tested positive for polonium-210 contamination.

Police and Health Protection Agency officers are at the Ashdown Park Hotel at Wych Cross, near Crowborough.

Mr Scaramella, the first person to test positive since Mr Litvinenko's death sparked a radiation alert, is not thought to be suffering physical symptoms but the amount found is "likely to be of concern for his immediate health".

He met Mr Litvinenko - who died last week at a London hospital - at sushi restaurant Itsu in central London on the day he fell ill.

Mr Scaramella is involved in an Italian parliamentary inquiry into KGB activity and was sufficiently worried by the contents of an email to ask for advice from Mr Litvinenko.

The Health Protection Agency said it was "continuing to provide expert advice on the public health issues surrounding the death of Mr Alexander Litvinenko".

A spokesman went on: "The Health Protection Agency can also confirm it was informed this morning that tests have established that a further person - who was in direct and very close contact with Mr Litvinenko - has a significant quantity of the radioactive isotope Polonium-210 in their body.

"This person is now to be investigated further in hospital.

"The Health Protection Agency continues to reassure members of the general public that the risk of having been exposed to this substance remains low.

"Our advice remains to members of the public that anyone who was in the Itsu restaurant or who was in The Pine Bar or the restaurant of the Millennium Hotel on November 1 should contact NHS Direct on 0845 4647."

A Cabinet Office spokesman said: "Clearly there is another trail that the police have now got to work out and for the agencies to go and examine.

"We will be looking for up-to-date information about where he's been and what he's been doing."

The spokesman confirmed the Italian government had been told of the latest development.

He said: "They have the same predicament about airlines that we faced because Mr Scaramella flew out of the country."