Will US raze Moscow embassy?

President Reagan has recommended to Congress that the United States tear down its new embassy building in Moscow and start over. The recommendation, announced yesterday, comes after extensive congressional investigation and a State Department-commissioned study by BDM Corporation, an engineering firm. The studies concluded that it is not technically feasible to remove all the bugging devices that the US says the Soviets built into the structure.

Another idea was to try to build ``secure'' rooms within the bugged structure, but that, too, was not deemed possible.

The President's recommendation is the first official step toward settling the problem. Now for the hard part: How will Congress come up with the exorbitant amount of money required? And how will the US keep the Soviets from bugging the new building?

According to a knowledgeable State Department official, the cost of razing the nearly completed building and constructing a new one could be as high as $300 million, a record for a new embassy.

Security measures account for the high cost. The plan is to construct the components of the new building in the US and transport them to Moscow for assembly, the State Department official says. At all times, US citizens with security clearances will guard the components and building site.

Construction on the existing building was halted in the summer of 1985, when US inspectors found eavesdropping devices implanted in floor planks.

Originally, the new embassy complex was to cost $90 million and be finished in 1983. Now officials do not expect completion before 1993. That means the embassy staff must make do with their current accommodations - a cramped, crumbling structure that has had two fires in the past year - for five more years.

The US government has not formally asked permission from the Soviets to proceed with its new plan for the embassy, but diplomats do not expect any snags. ``They have made the right murmurings'' when the subject has come up in diplomatic contacts over the past year, a State Department official says.

Meanwhile, State Department officials say Soviet diplomats in Washington will not be allowed to occupy their long-finished new embassy until US officials are able to move into a new building in Moscow.