GENEVA, FEB. 18 -- A senior Soviet official, speaking on the eve of a trip to Moscow by Secretary of State George P. Shultz, today accused Washington of hurting the strategic nuclear arms talks by pursuing its antimissile space defense program. But a U.S. spokesman countercharged that the Soviets had delayed the talks by refusing to discuss a U.S. draft treaty on space weapons.

The verbal exchange was initiated by Soviet Deputy Foreign Minister Vladimir Petrovsky, who said "it is difficult to forecast" how the negotiations will proceed because of the deadlock over Reagan's Strategic Defense Initiative (SDI) project.

Petrovsky said in a speech to the 40-nation Conference on Disarmament here that Moscow is not demanding that Washington scrap the SDI program, popularly known as "Star Wars." But he said the project must be limited to conform with the 1972 Anti-Ballistic Missile treaty, which prohibits advanced testing or deployment of such systems.

Because Washington insists on pushing forward with SDI, the negotiations have "noticeably deteriorated" and "it is difficult to forecast" how they will proceed, Petrovsky said.

U.S. spokesman Terry Shroeder said that "despite progress at the Washington summit on strategic arms control, the Soviets have slowed the pace and even backtracked in some areas" by refusing to engage in key working group discussions.