Haig says Soviets replied to Reagan letter on arms

Secretary of State Alexander M. Haig Jr. said the Soviet Union replied to a letter from President Reagan calling for new negotiations to reduce strategic nuclear weapons.

Appearing on CBS's ''Face the Nation,'' Mr. Haig chose not to disclose details of communications between the two countries, but said it was anticipated that a date for the opening of the nuclear talks would be set through diplomatic channels ''hopefully before too long.''

He also confirmed that informal diplomatic discussions had been held about a possible meeting between himself and Soviet Foreign Minister Andrei Gromyko at next month's disarmament conference in New York.