High-level Argentine officials today appeared to be edging away from the country's hard-line stand on negotiations to end the Falkland Islands crisis.

For the second time in two days, both Foreign Minister Nicanor Costa Mendez and Foreign Ministry cabinet chief Gustavo Figuero have strongly emphasized that Argentina is not demanding that Britain recognize Argentine sovereignty over the South Atlantic islands as a precondition to negotiations.

Figuero said in a broadcast interview this morning, "What we want is that precautions are taken so that these negotiations inexorably conclude with the recognition of our sovereignty."

Well-informed government sources said today that Argentina is still seeking implicit assurances that Argentine sovereignty will be recognized. But the sources added that the military government is now willing to be more flexible about the strengths of these precautions."

Renewed British shelling this morning did not prevent Argentine officials here from expressing cautious optimism about progress in talks being conducted by U.N. Secretary General Javier Perez de Cuellar.

Government officials maintained that there was a new atmosphere of flexibility in the military government here in looking for possible formulas to end the crisis.

Argentina, one informed government source here said, in the face of recent charges that it has been intransigent in the talks, "is seeking to prove that we're flexible and it is Britain that is intransigent."

Argentine government officials reported that British warships shelled Argentine positions three times last night and today. The attacks came at 9 p.m. EDT yesterday and shortly before 2 a.m. and 9 a.m. today. A communique issued by the military command said the last two bombardments lasted only 15 minutes and added, "Our forces repelled the aggressions."

Argentina is being represented in New York by the undersecretary of foreign affairs, Enrique Ros, who met today again with Perez de Cuellar, officials said here. Argentina and Britain were separately submitting new proposals for a possible settlement in the 5 1/2-week-old crisis, government sources said, and Perez de Cuellar was attempting to compile the suggestions into a plan both sides could accept.

Under the terms of the talks, Perez de Cuellar was keeping the proposals of the two governments secret from each other. But Argentine sources said here today that they had received no indication yet of great flexibility by Britain.

Costa Mendez, speaking to reporters on his way to a late-night meeting with President Leopoldo Galtieri, said he had a "moderate and reasonable hope" in Perez de Cuellar's negotiations.

In the past, Argentina has taken the position that if Britain did not recognize Argentina's sovereignty immediately, Argentina would have to have a superior position in any temporary administration that was established for the islands. That stand was outlined in a letter from Costa Mendez to U.S. Secretary of State Alexander M. Haig, Jr. during U.S. mediation efforts.

In addition, Argentina has said that negotiations would have to have a fixed time limit after which sovereignty would automatically be transferred to Argentina if there were no agreement.

The outlines of the proposal being discussed at the United Nations call for a temporary U.N. administration in which Argentine and British officials would play an equal role, according to sources here. The plan also does not deal with the issue of sovereignty in any way.

Argentina could now accept a temporary administration for the islands with Britain in which British and Argentine officials played an equal role, government sources said here today. In addition, Argentina would not necessarily demand that sovereignty be transferred automatically if the negotiations failed after a fixed period, these sources said.

Instead, Argentina has submitted a series of new proposals to Perez de Cuellar that include a variety of ways in which Argentina would obtain the kind of guarantee it is looking for, sources said. Among such proposals are one in which Argentina would purchase the Falkland Islands Co. from Britain, thus obtaining control over most of the land in the disputed territory. Other proposals could fix time limits on the length of negotiations and provide some mechanism for settling the conflict if an agreement was not reached by the deadline, sources here said.

Costa Mendez met this morning with the ruling military junta to discuss the negotiations, and this afternoon held a lengthy working session with high military aides from the presidental palace. Argentine officials said that Perez de Cuellar was expected to present a proposed solution drawn from the ideas submitted separately by Argentina and Britain in the near future.