A police inquiry was ordered today into the disappearance of the navigation logs of the British submarine Conqueror, which sank the Argentine cruiser Belgrano during the 1982 Falklands war.

The investigation was ordered by the director of public prosecutions after Defense Secretary Michael Heseltine reported to Parliament today that a Navy inquiry failed to "locate the missing logs or identify a proven explanation for their disappearance."

The missing six-volume log is the second key document from the submarine that has disappeared. Two weeks ago it was acknowledged by the ministry that the submarine's signals log, the one that records communications to and from the vessel, had been routinely destroyed because they normally are not kept permanently.

The Argentine cruiser was sunk on May 2, 1982, with the loss of 368 lives. At the time, Prime Minister Margaret Thatcher and her then defense secretary, John Nott, had said the vessel was sunk because it was closing in on, and posed a threat to, the British fleet that was nearing the Falkland Islands, which had been invaded by Argentine forces.

At the time of the sinking, there was overwhelming support by the British people for the move, and opinion polls still show that a substantial majority believes the cruiser should have been torpedoed.

But critics who have questioned the circumstances surrounding the sinking from the start in recent months have forced to the surface several facts and documents that have led to claims that the government has been engaged in a cover-up of the circumstances and did not tell Parliament the truth immediately after the attack.

Thatcher, in recent weeks, has acknowledged that the cruiser had been heading away from the task force for 13 hours before it was torpedoed, but she maintains that the course was irrelevant and the threat still existed.

When it was acknowledged that the communications logs had been destroyed, Labor Party Member of Parliament Tam Dalyell, who has been the most persistent pursuer of the government on the issue, asked, "Is it not astonishing that a key record of the biggest engagement in which the Royal Navy has been involved since 1945 should simply have been destroyed as a matter of routine?"

The communications records are of interest because the Belgrano was sunk several hours after the order was given, and an unanswered question is whether and when the government was aware of the ship's change of course.

Today, Labor deputy George Foulkes, who also has been a steady critic of the action, said the failure of the Navy to find the navigation logs "implicates the government in a major cover-up."

Heseltine said today that there were several possible explanations for the loss of the navigation logs, including the possibility that they inadvertently were destroyed. But he said it was "unlikely" that they were lost in transit between the submarine and the ministry or that they were mishandled at the defense records office. Heseltine said "there is no proof that the logs ever left HMS Conqueror."

Heseltine and Thatcher have denied strenuously any cover-up and have attributed the continued harping on the case to left-wing political interests. The most detailed account of the ship's action is said to be in the captain's log, which Heseltine has indicated is in ministry hands.