With London still reverberating from yesterday's revelations that the queen's long-time personal art curator had been a Soviet spy, new questions arose today over the "missing link" in the espionage scandal.

The suggestion that there may be yet another spy came from a Labor member of Parliament, Christopher Cryer, who has asked Prime Minister Margaret Thatcher to consider starting an investigation of Dr. Wilfrid Mann, a former British nuclear physicist now living in Washington, for alleged "connections" with Guy Burgess and Donald MacLean, former Soviet spies in the British government.

Mann, principal scientist for the U.S. National Bureau of Standards' radioactivity group, said in a statement issued through his office in Washington today that efforts to identify him "as the nuclear physicist who functioned as a Soviet spy" were "completely unwarranted by the facts." It did not address his involvement, if any, with the Burgess-MacLean case.

His statement said that "the British and U.S. governments are in full possession of all the facts" and that his case "has been reviewed" and he has "been assured that there is no question about his loyalty." Mann could not be reached directly for comment.

A statement issued by C. L. Haslam, general counsel of the Department of Commerce, the parent agency for Mann's bureau, said Mann "has been a long-standing and esteemed employee of the National Bureau of Standards. The Department of Commerce has no question concerning his loyalty to the United States."

The allegations here have added fuel to the growing cry of protest that greeted the government's announcement that Anthony Blunt, a Soviet spy in British intelligence from 1940 to 1945, was given immunity from prosecution in 1964 by British officials and allowed to continue in his position as Surveyor of the Queen's Pictures after he confessed his treason. p

In a statement to an astonished House of Commons yesterday, Thatcher outlined how Blunt had acted as a talent spotter for the Soviet secret service while teaching at Cambridge University before World War II, had "passed information regularly to the Russians" while working for British intelligence during the war, and helped Burgess and MacLean escape to the Soviet Union in 1951 when they were about to be arrested as Soviet spies.

Blunt confessed his crimes secretly to the British only after being given immunity from prosecution in 1964, according to Thatcher, and was then allowed both to keep his knighthood and to continue as Queen Elizabeth Ii's personal adviser on her huge art collection.

After Thatcher's revelations yesterday, Buckingham Palace stripped Blunt of his knighthood.

Opposition Labor members of Parliament are calling for a full debate in the House of Commons Monday over the issue of Blunt's treason and why he was given immunity from prosecution.

Their calls for a debate have been strengthened by questions over whether and when Queen Elizabeth II was told that the curator of her art collection was a former Soviet spy.

Statements from Buckingham Palace first said that it could be assumed that the queen knew of Blunt's treason when he confessed in 1964. Palace spokesmen are now saying that the matter is a private one for the queen only and refuse to make any further statement.

Further questions were raised today when past prime ministers Lord Home and Harold Wilson issued statements saying they were never informed about Blunt's confession of treason.

Blunt has disappeared, and Labor members of Parliament are accusing the Tory government of being part of an "establishment conspiracy" to protect Blunt by tipping him off. A government official said today that Blunt had been warned of the impending ministerial statement as a "common courtesy."

The British press has uniformly condemned past British governments' handling of the Blunt affair. The Times and other leading papers have all critized the decision made in the past to allow Blunt to continue in his capacity as Surveyor of the Queen's Pictures after he had confessed his treason. A Daily Telegraph editorial said today, "The course taken was most damagingly wrong."

Interest in the Blunt affair was further spurred today when British author Andrew Boyle, whose book on Soviet spies in the British government, "The Climate of Treason," touched off the recent disclosures, said that he knows of at least 25 other British officials who spied for Russia during World War II.

Boyle claims that besides a Soviet spy in British intelligence who is now known to have been Blunt, there was another Soviet spy, code-named "Basil," during the war, who, as a British nuclear physicist, worked in Washington after World War Ii.

Mann's statement denying the espionage allegations said that Mann was attached to the British embassy in Washington from 1949 to 1951 as a nuclear physicist. Burgess and another Soviet spy, Kim Philby, were stationed there at the same time.

The unnamed spy was uncovered by the CIA, Boyle claims, and turned into a double agent against the Russians, Boyle says that "Basil" told the CIA that Burgess and MacLean were also Soviet spies. In return for his help, Boyle said yesterday, the CIA assured "Basil" that he would receive U.S. citizenship and employment.

Blunt's lawyer today said he believed Blunt was still in Britain and might give a public statement about his past next week.