Apr. 13, 1962 - Premier Khrushchev has spurned what appeared to be the final offer by the U.S. and Britain to sign a nuclear test-ban treaty that would avert the renewal of Western testing in the atmosphere later this month. In a message sent yesterday to Prime Minister Macmillan, Mr. Khrushchev again branded the Western call for a treaty that would be enforced through international inspection as an attempt to expose the Soviet Union to espionage. The Soviet leader asserted that President Kennedy and the Prime Minister had decided to go ahead with nuclear testing in the Pacific as planned. Mr. Khrushchev’s statement seemed to indicate that the Soviet Union would conduct another series of nuclear tests of its own.