The United States and the Soviet Union have agreed to new talks aimed at banning the testing of killer satellites in space, informed sources said yesterday. There is a hope, but no certainty, that the negotiations could be completed in time to be signed at a U.S.-Soviet summit meeting convened for the signing of a new strategic arms limitation treaty (SALT).

The forthcoming talks on satellites were made known as Secretary of State Cyrus R. Vance and Soviet Ambassador Anatoliy F. Dobrynin met last night at the State Department in an effort to make additional progress toward completion of the SALT accord.

The sources said the anti-satellite (ASAT) negotiations had been discussed in earlier meetings between Vance and Dobrynin. The subject is pertinent to SALT because satellites with photographic gear and other sophisticated devices are an important means of verifying the provisions of a SALT agreement. Two rounds of ASAT negotiations have been held between the two nations, but without major results.

U.S. sources made it clear that Washington will not back away from its position that the testing of killer satellites should be banned.

Last night's meeting of Vance and Dobrynin on SALT lasted a little more than 1 1/2 hours. Afterward, the State Department announced that another meeting will be held in a few days. "Some final items remain to be cleared up," said department official Thomas Reston.

Reston added that the two sides are closer to agreement than before and he repeated Dobrynin's statement to reporters Saturday that they are "closer and closer . . . very close" to a conclusion. Dobrynin, leaving last night's meeting, said only that it confirmed his statement of two days before.

A date for the next SALT meeting has not yet been set.

Shortly before the 6 p.m. session with Dobrynin, Vance met with Secretary of Defense Harold Brown and presidential assistant Zbigniew Brzezinski for about an hour at the State Department. The meeting is believed to have concerned the U.S. responses to the latest Soviet proposals, presented by Fobrynin to Vance on Saturday morning.

Earlier yesterday, State Department spokesman Hodding Carter said "we continued to make progress" toward a final resolution of the few remaining issues in the long-running negotiations over strategic nuclear arsenals.