Vietnam is raising new impediments to a plan to send its "reeducation camp" inmates into exile in the United States, Rep. G.V. (Sonny) Montgomery (D-Miss.) said yesterday.

But Montgomery, who led a six-member congressional delegation to Hanoi earlier this month, said it remains his impression that "the Vietnamese do want to let the camp inmates out."

Montgomery made the comments in a telephone interview from Mississippi as the State Department criticized recent changes in Vietnam's position as "very disappointing."

Montgomery said his discussions in Hanoi Dec. 9-11, like the talks in Hanoi last weekend of Reps. Stephen J. Solarz (D-N.Y.) and Robert G. Torricelli (D-N.J.), included a demand by Vietnamese officials for a "commitment or guarantee" about the future activity of any camp inmates who might be released to emigrate to the United States.

The Vietnamese officials referred to the inmates as "criminals" who are "intransigent" and "bellicose," according to the report of the delegation led by Montgomery, "and expressed a strong fear that the prisoners, if released, would independently or with the support of the United States conduct anti-Vietnamese activity both in America and Indochina."

The report quoted the Vietnamese officials as saying that release of the camp inmates could be arranged "only by negotiating such an agreement" against future anti-Vietnamese activity.

Montgomery said he and his delegation replied that any inmates released to come here would be subject to the U.S. Neutrality Act making it a crime to conspire on U.S. soil against a government with which the United States is not at war.

The lawmakers said any Vietnamese who came here "would be too busy working to support their families" to engage in international intrigue.

The most serious stumbling block to the emigration plan, in Montgomery's view, is Vietnamese insistence on treating the inmates as "criminals" and the U.S. desire to treat them as normal refugees under existing administration programs.

State Department spokesman Alan Romberg noted that Vietnam itself first raised the possibility three years ago of releasing the camp inmates. Many of the inmates, estimated at between 6,000 and 15,000, were officials of the U.S.-backed Saigon government that collapsed in mid-1975.

Secretary of State George P. Shultz announced Sept. 11 that the U.S. administration is willing to grant entry to as many as 10,000 political prisoners from the Vietnamese camps. U.S. and Vietnamese officials discussed the matter in meetings in Geneva, Switzerland and New York in October.

Romberg said the United States is prepared to meet again with Vietnam to negotiate on the release of the reeducation camp inmates.