President Daniel Ortega said tonight that he was willing to meet with U.S. Secretary of State George P. Shultz in Montevideo, where both arrived today to attend the inauguration of Uruguay's president Friday.

"We have the hope that we can talk. That at least," Ortega told reporters on arrival in Montevideo. Shultz earlier had told reporters traveling with him to Uruguay that he also was willing to meet with Ortega.

Nicaraguan Vice President Sergio Ramirez expanded on a new peace initiative announced here last night by Ortega, saying in a Managua interview that Nicaragua was prepared to turn over to the Contadora countries a man currently in jail here whose claim for political asylum caused a serious diplomatic dispute with Costa Rica.

That dispute led to cancellation of last week's scheduled meeting of the Contadora group, the four Latin American governments that are seeking to negotiate a peaceful settlement of conflicts among five Central American countries.

Ramirez said that Jose Urbina Lara, who was arrested by Nicaraguan authorities Dec. 24 under disputed circumstances, will be released within a week as a concession demonstrating the disposition of the Sandinista government here to negotiate solutions in Central America.

"We are going ahead with this to demonstrate our will to make serious concessions," Ramirez said. "We are the only country involved in the Central American conflict that is really taking concrete steps and not solely making promises."

Ramirez maintained that the Sandinistas are winning on all fronts in their battle to end Reagan administration support for anti-Sandinista rebels.

"The Reagan administration is losing its battle in Congress. There is a battle for public opinion that the administration is not winning. There is a war here in Nicaragua against the counterrevolution, which we are winning."

He added, "The prospects for us are good and these newly announced initiatives are going to open a new avenue."

The decision to release Urbina Lara was one of several proposals Ortega announced last night. The Sandinistas also promised to send home 100 Cuban military advisers, and to refrain for an indefinite period from acquiring new weapons systems, including sophisticated interceptor aircraft.

In Washington today, Reagan administration officials minimized the importance of the Sandinista proposals and described them as propaganda lacking substance.

"For those who simply want our heads, there is no proposal that will be sufficient," said Ramirez. "The only sufficient proposal will be our heads in a basket. We defy other Central American countries involved in this conflict and the government of the United States to make this type of 'empty' proposal.

"A good kind of empty proposal would be that the Reagan administration cease its financial support of the counterrevolutionaries," he said.

Ramirez insisted that the Sandinista offer to send home 100 Cuban military advisers was a significant concession.

"It is an important percentage because the number of Cuban advisers in Nicaragua are not counted in the thousands as is said in Washington, but in the hundreds," he said. Reagan administration officials have said there are as many as 3,000 Cuban military advisers in Nicaragua, while Cuban President Fidel Castro and Sandinista officials have insisted that there are only 200 such advisers. Ramirez would only say that there were "hundreds."

Diplomatic sources here estimated that there are about 6,000 Cubans here. They noted that while most are teachers, 1,500 Cuban teachers went home in November and are not expected to return. Ramirez said that 550 to 600 of the Cubans now here are medical personnel and that Nicaragua cannot do without them.

Ortega was quoted today as saying, en route to Uruguay, that the number of Cuban military advisers was less than 1,000.

Some western diplomats in Managua agreed with Reagan administration officials that the Sandinista intiative was a propaganda move rather than substantive concessions that might further the peace process.

"All they are saying is that they won't do what they are unable to do anyway," said one Western European diplomat. "The Soviets aren't going to give them planes anyway, they have the weapons they need, and the Cubans want to reduce their presence here anyway."

Another said, "It is another propaganda coup. They are good at it. They always catch the Americans on the wrong foot." Washington Post correspondent Jackson Diehl, in Montevideo, contributed to this story.