Britain secretly alerted airlines and airports about a possible terrorist attack two days before a bomb blew Pan Am Flight 103 out of the sky over Scotland, the Transport Department has announced.

It said in a statement Wednesday night the alert gave precise details of a new type of bomb, hidden in a radio-cassette player, similar to the device that on Dec. 21 destroyed Flight 103, killing all 259 people aboard the jumbo jet and 11 on the ground in Lockerbie.The alert was similar to an earlier warning sent out on Nov. 22 but included a photo of the radio-cassette player, the department said later.

Flight 103 originated in Frankfurt, West Germany, then changed planes at London's Heathrow airport before heading for New York.

A radio-cassette player containing plastic explosives and a device that could be set to detonate the bomb at a given altitude was found in October during raids by West German authorities in which 13 alleged members of the Syrian-backed Popular Front for the Liberation of Palestine-General Command guerrilla group were arrested.

Pam Hanlon, a Pan Am spokeswoman in New York, said Thursday: "There is indeed a memo dated Dec. 19, but we did not receive it until Jan. 17. I am not going to say more than that." She said she did not have the memo in front of her so she would not talk about what it contained.