A new book about to be published here reopens the spy scandal involving Soviet agents inside the British government -- Kim Philby, Guy Burgess and Donald MacLean -- with new allegation that two other Britons spied for the Soviets in the case.

"The Climate of Treason," by the respected British biographer Andrew Boyle, says one of the hitherto unpublicized Soviet spies helped British diplomats Burgess and MacLean escape to the Soviet Union in 1951.

Boyle says the other Soviet agent was discovered and "turned" by the CIA, which used him to help uncover the other spies in the Philby case and to feed misinformation to the Soviets.

A British Foreign Office spokesman today refused to comment on Boyle's allegations.

Burgess and MacLean both had worked in the British Embassy in Washington. Philby was head of British counterintelligence against the Soviet Union and also the British liaison with the CIA and FBI in Washington from 1949 to 1951.

After his defection in 1963, Philby was found to have been a Soviet agent for over 30 years. John le Carre's novel "Tinker, Tailor, Soldier, Spy" is based in part on Philby's career.

Boyle, whose book is being serialized in the Sunday Observer newspaper, says he relied heavily on interviews with former CIA and British agents involved in the case. He also says he used FBI and CIA files gained under the U.S. Freedom of Informatin Act.

The book says one of the Soviet spies was a British physicist working on joint nuclear research in Washington in 1947. This spy, code-named "Basil," allegedly was discovered by the CIA acting on a tip from Israeli intelligence. After using "Basil" as a double agent against the Soviets, Boyle says, the CIA gave him American citizenship and he now lives in the United States.

Because of stringent British libel laws, Boyle does not name the two alleged agents except by their code names.

The other Soviet spy, Boyle says, was a British intelligence officer in London, code-names "Maurice," who warned Burgess and MacLean they were about to be arrested. The question of how they evaded arrest has long troubled students of the case.

Boyle's book says "Maurice" confessed two years after the defections. In return, and to avoid further public scandal, Boyle says, British authorities granted a pardon and "Maurice" holds a prominent place in British public life.

Although Boyle does not identify "Maurice," he describes him as a left-wing Cambridge University teacher in the 1930s who was a close friend of Burgess.

The only person mentioned in Boyle's book who could fit such a description is a former director of a well-known London institute of fine arts. Boyle describes the man as a close friend of Burgess and a former intelligence officer.

The British satire magazine Private Eye said in a recent issue that a libel lawyer representing the man called the publishers of Boyle's book, Hutchinsons, asking to see the book before it was published.

British libel laws prevent the naming of a person, without corroborating evidence, in a way that may harm his reputation.