A Royal Canadian Mounted Police detective arrived here today to assist Japanese police in the investigation of possible links between the destruction of an Air-India jumbo jet over the Atlantic Ocean and an explosion in a Tokyo airport Sunday.

The detective joined an official of Canada's Transport Ministry investigating the blast at Narita airport, the Canadian Embassy said.

There was mounting speculation here that the Tokyo airport blast was caused by a bomb meant for an Air-India jet that took off from the airport several hours after the explosion. The luggage that exploded had arrived in a Canadian Pacific Airlines flight, and two men using the names A. Singh and L. Singh had made reservations on that flight. Apparently neither of them boarded it.

Authorities in the United States and Canada are hunting for two Sikhs identified as Ammand Singh and Lal Singh in connection with the two aircraft incidents. The men had earlier been accused by the FBI of plotting to kill Indian Prime Minister Rajiv Gandhi when he visited the United States earlier this month.

[Canadian authorities close to the investigation said Wednesday, however, that they had determined that the A. Singh and L. Singh who had made reservations on the Canadian Pacific flight, but never boarded it, were not the two men sought by the FBI, Washington Post correspondent Herbert H. Denton reported from Ottawa. The sources added, however, that the Canadian probe is focusing on the two Singhs along with other individuals. They said the two men are thought to be Sikhs and naturalized Canadian citizens and are believed to have connections to the All-India Sikh Students Federation.]

Anonymous callers claiming to represent groups called the Sikh Students Federation and the Kashmir Liberation Front claimed responsibility Sunday for the crash of the Air-India plane.

A Northwest Orient Airlines official said tonight that a man traveling under the name of A. Singh flew to Tokyo from the United States Sunday aboard a Northwest Orient Airlines jet, then transferred to another jet of the same company and went on to Manila. But there was no evidence that he was the same A. Singh who had made a reservation on the Canadian Pacific flight.

In recent days, attention has focused on the movements of the two Singhs, based on names showing up on airline manifests and reservations records. However, since almost all Sikh men use the name Singh, it is by no means certain that the names found in these documents correspond to the two wanted men.

According to Canadian newspaper reports, a passenger identifying himself as A. Singh presented himself at the airline's counter in Vancouver before the Canadian Pacific flight to Tokyo, checked one or more pieces of baggage aboard it, but then disappeared without getting aboard himself.

Earlier, onward reservations from Tokyo had been made in both names aboard Sunday's Air-India Flight 301, according to the airlines' Tokyo manager, D. Lingam. It was scheduled to leave Tokyo for Bombay several hours after the arrival of the Canadian Pacific jet.

This has led to speculation that any time bomb aboard the Canadian Pacific jet was placed there in expectation that the baggage it would be transferred to the Air-India jet in Tokyo but it exploded early. Japanese police have said the blast appears to have occurred among transit baggage.

[Off the coast of Ireland, pieces of wreckage were brought ashore, but no more bodies were recovered from the Air-India jumbo jet that plunged into the Atlantic on Sunday with the loss of 329 lives, Reuter reported.]ases full of work and check with their offices every few hours.