Members of the new Nicaraguan government today proclaimed the defeat of the "last bulwark of Somaza's dictatorship" as his National Guard ceased active resistance to the rebel Sandinista army.

Several members of the cabinet of the "government of national reconstruction" and about 200 supporters opened and closed an emotional news conference here by singing the Nicaraguan national anthem and shouting the slogans of the Sandinista guerrillas who defeated the National Guard after several years of warfare.

Although the Sandinista slogans got the loudest cheers the cabinet members reflected the broad political base of the opposition to Somoza.

First to speak was businessman Gilberto Serrano of the Superior Council of Private Enterprise, the business federation that will have six members in the 33-member legislative body of the new government.

Joaquin Cuadra Chamorro, a lawyer and finance minister of the new government, read its lengthy "fundamental statute," which dissolved the old congress, armed forces and political police and gave the legal outline of how the new junta and its legislative Council of State will govern Nicaragua until elections are held.

He said a constitutional assembly would be elected as soon as "the job of reconstructing the country permits."

Junta spokesman Manuel Espinoza announced that despite a breakdown in plans for a transfer of power, the junta would still honor its pledge to guarantee the safety of Somoza supporters who wish to flee the country.

Leonel Arguello Ramirez, named by the junta to a key economic post, appealed to all the businessmen and argicultural workers who had left the country to return "so tomorrow we can go back to work...and feed our brothers."

Earlier in the day, officials of the junta lobbied vigorously to obtain official recognition from other Latin American governments.

The first two countries to recognize the new government today were Costa Rica and Mexico. Several other countries had extended recognition during the fighting.