Professor Pontecorvo was last seen seven weeks ago in Finland

England have

MI5 has been brought into the hunt for the missing atomic scientist Bruno Pontecorvo who has not been seen for about seven weeks.

Professor Pontecorvo and his family arrived in Finland at the beginning of September but they have since disappeared. There is speculation the family may have gone to Russia.

The professor had recently left his post as a principal scientific officer at Harwell atomic laboratory and was due to begin a new job at Liverpool University in January.

His disappearance - coming just 10 months after another Harwell scientist, Klaus Fuchs, confessed in January to spying for the Soviet Union - is bound to raise concerns.

The Minister of Supply, George Strauss, has told MPs the professor had had only limited access to 'secret subjects' for some time.

But he admitted it would have been possible for the Professor to gather information, at Harwell or while he was in Canada, which could be of value to the enemy.

He said Professor Pontecorvo had been screened several times in the last few years by security officers.

Professor Pontecorvo was born in Italy, moved to France in 1936 and from there to the United States in 1940. In 1943 he became a member of the joint Anglo-Canadian atomic energy team at Montreal.

He was posted to Harwell in January 1947.

Information on Professor Pontecorvo's disappearance has been passed to the United States.

The professor's sister, Anna Pontecorvo, who lives in Hampstead in north London, travelled with her brother, his wife and three sons to France and Italy in July.

She said her brother had not mentioned any plans to go to Russia during the time she spent with them.

However, a passenger in the airliner which took the family from Stockholm to Helsinki said that during the flight the Pontecorvos' five-year-old son Antonio had told him they were going to Russia.

There are direct flights from Helsinki to Leningrad and Moscow.  

Protesters formed a human chain and charged at the police

 1968: Police clash with anti-war protesters

Trouble has flared in Grosvenor Square, London, after an estimated 6,000 marchers faced up to police outside the United States Embassy.

The protesters had broken away from another, bigger, march against US involvement in Vietnam but were confronted by a wall of police.

The breakaway group, led by the Maoist Britain-Vietnam Solidarity Front was almost thwarted by the march organisers who were aware of the plan and feared violence would erupt.

Once in Grovesnor Square the protesters formed a human chain and charged at the police wall but failed to break through and, after three hours of stalemate, they all dispersed.

In the streets surrounding the square fireworks and other missiles were thrown but no injuries were caused and police considered them to be isolated incidents.

The rest of the march, organised by the Vietnam Solidarity Campaign (VSC), continued peacefully to Hyde Park.

At Downing Street, Tariq Ali of the VSC handed in a petition, signed by 75,000 to ask the government to stop supporting the US in its war against Vietnam.

The Home Secretary, James Callaghan, praised the demonstration saying "self-control was shown by the mass of the demonstrators."

He also praised the discipline and restraint shown by police.

"I doubt if this kind of demonstration could have taken place so peacefully in any other part of the world" he said.

Security for the march was high. A 1,000 strong team of police was stationed outside the US Embassy and policemen lined the route of the march with back-up following in coaches.

The turnout for the march was around 25,000, half the number predicted by police and organisers.

But, far from being disappointed at the low turnout Mr Ali said; "This is not the end. This is the beginning of the campaign."

thwart: hinder or prevent (the efforts, plans, or desires) of（阻礙；反對(duì)）