MANAGUA, NICARAGUA, SEPT. 7 -- President Daniel Ortega said today that he plans to be in Moscow celebrating the 70th anniversary of the Russian Revolution on Nov. 7, the day the Central American peace accord is to take effect.

The surprise announcement, which diplomats said was sure to draw criticism from Washington, was made following a meeting between Ortega and Vadim Zagladin, a special envoy of Soviet leader Mikhail Gorbachev.

Ortega said that Zagladin had given him a letter from Gorbachev in which the Soviet leader also pledged to provide Nicaragua with an additional 700,000 barrels of oil this year.

The Soviet Union has supplied virtually all of Nicaragua's oil since 1985. In May, however, it announced that it would cover only part of this year's requirements because of supply problems.

The cutback sparked a fuel crisis here that led Nicaraguan officials last month to appeal for urgent assistance from other countries. Even with the latest donation from the Soviet Union, Ortega said, Nicaragua would need more than half that amount from elsewhere to cover its basic needs until year's end.

In May 1985, following Ortega's first official visit to Moscow, President Reagan clamped a trade embargo on Nicaragua. The visit also helped Reagan drum up congressional support for the contra rebels battling the Nicaraguan government. Reagan has accused the left-wing Sandinista government of seeking to spread communist revolution throughout Central America.

Nicaragua depends heavily on Soviet Bloc economic and military assistance and has made no secret of its close ties with Moscow but has denied any intention of spreading revolution beyond its borders.

Speaking at a joint news conference, Zagladin pledged Moscow's support for the peace pact.