The official Soviet news agency Tass today criticized President Reagan's offer to share nuclear monitoring equipment with the Soviet Union as "a political maneuver aimed at evading a concrete answer" to the Kremlin's appeal for a ban on nuclear testing.

Tass also called Reagan's invitation to Soviet scientists to monitor U.S. nuclear explosions in Nevada next month a "propaganda gimmick" by the United States, designed "to camouflage its obviously negative stand on ending all nuclear explosions."

Reagan proposed sharing U.S. technology used to oversee nuclear explosions, and invited the Soviet observers to a Nevada nuclear test site in April in a letter to Soviet leader Mikhail Gorbachev released yesterday.

The Reagan proposal is of "a limited character," Tass said. It added that it concerns only "the technical problems" of verifying the U.S.-Soviet treaties on underground and peaceful explosions, signed in 1974 and 1976 but as yet unratified.

Thursday, Gorbachev announced an extension of the Soviet Union's seven-month-old nuclear testing moratorium beyond March 31, until the United States conducts a nuclear test. The extension was widely viewed here as a move to pressure the United States into complying with a testing moratorium, which the Reagan administration opposes.

Gorbachev indicated that progress on a nuclear test ban is one of his priorities for his next summit meeting with Reagan.

The opposing views on the ban have become an obstacle to setting a date for the summit, according to diplomatic sources here.

The two leaders agreed at their Geneva meeting in November to meet this year, but the Soviet Union has not yet responded to U.S. appeals to set a date. Soviet Premier Nikolai Ryzhkov and Secretary of State George P. Shultz discussed the test ban and the summit when they met in Stockholm today at the funeral of slain prime minister Olof Palme. They reportedly reached no conclusions.