Archaeologists examining the flagship of King Henry VIII, which sank in 1545 as it sailed to engage a French fleet and lay preserved in silt until it was raised in 1982, have discovered evidence of a powerful "supergun" aboard the vessel, it was reported Saturday.

Margaret Rule, the archaeological director of the trust examining the Mary Rose, told The Daily Telegraph that two powder chambers recovered by divers from the sea bed indicate a fire power not previously believed to have been aboard the pride of the Royal Navy.The 132-foot-long Mary Rose was dispatched from Portsmouth Harbor to engage a French fleet as Henry VIII watched from the shore. A sudden gale caused the newly delivered vessel to list. The ship's guns broke loose and the vessel disappeared in a minute.

Of the 700 crew aboard, only 40 were said to have survived.

"We believe the evidence indicates that when the ship sank . . . there was one supergun and perhaps a second on board," Rule said, noting one would have been positioned at the bow and possibly a similar weapon at the stern.

"Our research indicates each gun must have been over five meters (16.5 feet) long . . . and would have been capable of firing considerably further than the half-mile or so range of other wrought iron, breech-loading guns found on the Mary Rose," she said.

The other eight large main deck guns were less than half the length, she said.

Guns to accommodate chambers of the length recovered, Rule said, "would pose severe handling problems" for the Mary Rose. But she said there was no evidence to suggest that they had caused the vessel to keel over and sink.

The hull of the ship, raised in October 1982, is under restoration at the Porstmouth Royal Naval Dockyard. The solidified material of the original chambers was lifted from the site in 1985, but it was not until last year "when we realized we had something exceptional," Rule said.

"We decided that we had to be sure. We did not want to damage the credibility and reputation of the trust by publishing our findings prematurely," she told The Daily Telegraph. "Then the gulf crisis happened and we decided to wait until things quieted down."

Rule said the discovery of such a large gun was exciting but not necessarily surprising.

"There was a tremendous amount of secrecy and espionage in those days just as there is today about new weapons systems," she said. "The balance of firepower at sea was vital to England's survival, and we know extreme pressure was put on ordnance makers to increase the efficacy of their guns."