Argentina's defense minister said today that 368 crew members of the sunken cruiser General Belgrano are still missing, but searches continue off Tierra del Fuego.

Defense Minister Amadeo Frugoli told a press conference that of the 1,048 aboard when the cruiser was torpedoed Sunday by a British nuclear submarine, 680 have been rescued.

Frugoli said, however, that he could offer no actual casualty figures for either the cruiser or other military actions. He said the joint chiefs of staff would reveal them at a "timely" moment.

The press conference, the first offered by senior defense officials since the invasion of the Falklands April 2, appeared to have been called to stress that the Belgrano was outside of Britain's own exclusion zone around the islands and that the aging ship offered no threat to British forces when it was attacked.

In the diplomatic arena, Frugoli did say Argentina "is open to any diplomatic negotiation that could lead to a peaceful solution," but he added that any accord had to account for "our honor and our legitimate rights."

Frugoli, who is a lawyer, not a general, in the military-dominated government, said Argentine airstrips on the Falklands were in working condition despite British bombing raids

He said Argentina had not considered "the possibility of asking for military support from other countries," apparently referring to the Soviet Union. He refused to comment on reports that Brazil had agreed to sell Argentina two of its Bandeira naval surveillance aircraft.

Reports reaching Buenos Aires from Uruguay today said a Polish fishing boat was expected there late today carrying two Argentine pilots who survived the downing of their Canberra bomber during an attack on the British fleet.

The reports quoted the Polish Embassy in Montevideo as saying the Polish fishing boat had picked up the pilots. The Argentine military command has not acknowledged the plane was downed.

As reports from Britain indicated second thoughts there about the loss of lives in this week's fighting, Argentine officials sought to play up what they said was the unnecessary sinking of the cruiser. They charged Britain with violation of the standards of war.

Britain's explanation--that the Belgrano was a threat to Britain's task force--"lacks all validity and offends reason," said Frugoli.

There was no sign here that the heavy Argentina toll had weakened political support for the military defense of the islands, which have long been a popular patriotic cause here.

Leaders of the principal political parties, who had begun to renew their attacks on internal policies and even to question the timing of the invasion last week, have once again aligned with the military after this week's fighting.

With the civilian politicians echoing the strongest line of military leaders, the junta here is under little pressure to concede ground because of the losses so far, analysts said.