Pressure is mounting on both sides of the Atlantic for governments to fully reveal all warnings issued before the December bombing of a Pan American World Airways jet over Scotland, killing 270 people.

The demands intensified Sunday with the revelation that vital clues to identify the type of radio-cassette player rigged as a bomb that destroyed the Boeing 747 were omitted from a warning issued by Britain a month before the Dec. 21 disaster.Opposition Member of Parliament John Prescott demanded that Transport Secretary Paul Channon make a full statement on the issue to Parliament, and in New York a group called Victims of Pan Am Flight 103 called for a congressional investigation of the government's handling of warnings of a potential terrorist attack prior to the bombing that killed 259 people on the Pan Am jet and 11 residents of Lockerbie, Scotland.

"They had plenty of information and plenty of warning," said Herbert Ammerman of River Vale, N.J., spokesman for the group. "This organization is not going to go away. We're just asking for what is right."

About 100 members of the group met in Trumbull, Conn., Sunday to plan a memorial service April 3 in front of the White House, Ammerman said.

Ammerman said he sent a letter to President Bush last Wednesday asking that he meet with representatives of the group after the service.

"The only way our loved ones can have some justification is if we know exactly what took place," he said.

Ammerman's brother, Thomas, 36, of Old Tappan, N.J., was among those killed.

"We have banded together to find the answers to questions regarding responsibility for this tragedy, and to ensure that necessary security changes be implemented," said Paul Delude of Pomfret, Conn.

In London, Prescott said information that could have helped security officials identify a radio-cassette bomb of the type that destroyed Flight 103 was not included in a warning issued by the Transport Department Nov. 22.

U.S. officials issued a similar warning four days earlier, but a Federal Aviation Administration spokesman declined to discuss the contents of the telex for security reasons.