The Central Intelligence Agency "disagrees" with the Department of Defense over the Soviet threat to initiate use of chemical weapons against NATO forces in Europe, according to testimony presented to Congress last year.

The CIA believes "there is less [Soviet] intention to use chemical weapons and, therefore, probably less of a threat," Army Chief of Staff Gen. John A. Wickham Jr. told a closed session of the House Appropriations defense subcommittee last March, according to testimony recently made public.

Wickham added that the intelligence agency made its judgment "by looking at documents." The Army, he said, made its determination on the threat of Soviet use of chemical weapons because "we believe the capability is there."

Last year, Rep. John Edward Porter (R-Ill.), a leading critic of the administration's program to resume production of chemical weapons, arranged for two classified CIA briefings for members prior to votes on the issue.

Agency analysts reported that the Soviet military had cut back on reliance on chemical weapons, one source said, saying there was little tactical advantage to be gained from initiating use of chemicals over conventional weapons if the NATO forces had protective gear.

"We were overwhelmed on how good it was for us," a House aide opposed to the resumption of U.S. production of chemical weapons said yesterday of the CIA assessment.

The CIA assessment was in contrast to the results of a three-year, $890,000 Pentagon-financed contract designed to overcome congressional opposition to building chemical weapons. One of the studies under the contract was by a group of 21 retired admirals and generals. It found that the Soviet chemical weapons "threat is serious, the potential for use is likely."

After three years of balking at an administration request to resume chemical weapons production, the House eventually compromised with the Senate to permit production of new chemical shells to begin in 1987.

A new effort will be made this year to reverse that decision, House and Senate critics of the program said yesterday.

In a related action, Sen. David H. Pryor (D-Ark.), another opponent of chemical weapons production, yesterday called on Defense Secretary Caspar W. Weinberger to answer a series of questions on the $890,000 contract.

Pryor asked why one $70,000 contract went to an outside consultant to declassify the report by the former officers. "Is there no employe on the Defense Department payroll who could have performed this relatively simple task at no additional cost to the taxpayer?"