Minister raises questions about Putin after death of Litvinenko

President Vladimir Putin's credentials as a democrat were called into question by a cabinet minister yesterday, as police continued their investigations into the death of the former KGB agent Alexander Litvinenko.

Peter Hain, the Northern Ireland Secretary, said there had been "huge attacks" on liberty and democracy during Mr Putin's presidency and pointed to the "extremely murky murder" of Russian investigative journalist Anna Politkovskaya, who was a prominent critic of the President.

The death of the reporter was being investigated by Mr Litvinenko, who died last week, 22 days after mysteriously absorbing polonium 210, a rare and highly toxic radioactive material.

Mr Hain's assertions mean that tensions between London and Moscow - which other ministers have sought to play down - have now burst into the open.

The Home Secretary, John Reid, fuelled the emerging diplomatic conflict by saying that officers investigating the death now regarded the circumstances as "suspicious" rather than "unexplained".

The Department of Health revealed that up to 300 members of the public had contacted NHS Direct expressing concern that they may have been exposed to radiation.

A spokeswoman for the Health Protection Agency urged anyone else who was concerned to get in touch. However it was "very unlikely" that they would have absorbed any radiation, she said. Scientists at the agency were due to begin receiving urine samples for testing last night.

Mr Litvinenko's widow Marina, 44, son Anatole, 12, and father, Walter, were still struggling to cope with what happened, his friend Alex Goldfarb said.

"They are in deep mourning, but at the same time they are watching the TV and are anxious to find out who did it."

Another friend of Mr Litvinenko, the film-maker Andrei Nekrasov, described how the former "Russian muscle man" had been reduced to "screaming in pain" as he lay dying.

Polonium contamination was first found at Mr Litvinenko's home in north London last Thursday.

"High doses" were later found at other sites, prompting concern over public health. The former Russian spy, 43, had lunch on 1 November with the Italian "security consultant" Professor Mario Scaramella at Itsu, a sushi restaurant in Piccadilly where police believe Mr Litvinenko was poisoned.

It has since been reported that Professor Scaramella headed an organisation that tracked nuclear waste, including Soviet nuclear missiles left over from the Cold War. He strongly denies any involvement in the Russian's death.

After meeting the Italian, Mr Litvinenko went on to the nearby Millennium Hotel to see two Russians, Andrei Lugovoy and Dimitri Koytun. Both the restaurant and the hotel have since been sealed off.

Detectives are due to fly to Moscow and Rome this week to question Professor Scaramella and the two Russians.

Some security sources in Britain suspect that Russian agents - or a rogue element within the country's security services - were behind Mr Litvinenko's death.

According to some reports, in his last full interview from hospital, Mr Litvinenko named Viktor Kirov as the Russian agent responsible for monitoring him, although he did not accuse him of any direct involvement in his poisoning. Moscow has denied any role in the ex-KGB man's death.