President Reagan's "Star Wars" missile defense program is "rife with potential for conflicts of interest," as self-interested defense contractors gauge the project's feasibility and constituents of key members of Congress benefit from a disproportionate share of the $1.6 billion in initial research work, according to a study released yesterday.

"The danger lies in the program being launched on the basis of economic benefits to key contractors and constituencies whether or not it is proven worthwhile on national security grounds," the study by the Council on Economic Priorities concluded.

The council, a nonprofit public interest group that has criticized Reagan's defense policy in the past, urged Congress to create an independent panel of experts to assess, on an annual basis, the progress of Star Wars research, for which Reagan wants $26 billion in the next five years.

The program, officially known as the Strategic Defense Initiative (SDI), is gaining an "unstoppable economic and political momentum," the study said, noting that top defense contractors, who stand to gain most from deployment of a strategic missile defense, have been awarded contracts to develop and assess the weapon's technical feasibility.

Ten of the nation's largest defense firms -- led by Boeing, Lockheed, McDonnell Douglas and LTV -- have reaped 87 percent, or $1.4 billion, of SDI research contracts awarded since 1983, contributing significantly to their business, the report said.

"It is an anomaly to put people who will get money later on in charge of studying feasibility," Richard L. Garwin, a council adviser and former DOD consultant, told a news conference yesterday.

He noted that initial research on intercontinental ballistic missiles in the early 1950s was performed by nonprofit organizations with no direct financial interest in deployment of the weapon.

The study said SDI research also poses a conflict for members of the congressional appropriations and military oversight committees, whose votes are crucial to the future of the controversial system and whose districts have received 77 percent of the research contracts already awarded.

The program has been "well targeted to influence" those legislators, said the council, adding that contractors in their states have received an average of six times more contracts than contractors elsewhere.

Four Republican members of the key committees represent constituencies receiving the largest share of SDI research work, according to the study. Contracts worth $727.9 million have gone to California, which has a senator, Pete Wilson, on the Armed Services Committee. Of that statewide total, the study added, $236.6 million has gone to the district of Rep. Robert E. Badham, who is on the House Armed Services Committee.

Contractors in Sen. Jeremiah Denton's state of Alabama have been awarded $161.4 million in SDI contracts, and firms in Sen. Phil Gramm's state of Texas have received $212 million worth, the report said. Gramm and Denton are on the Armed Services panel.

Paul C. Warnke, a council adviser and former director of the U.S. Arms Control and Disarmament Agency, said in a preface to the report: "What we see happening today is the rapid conversion of the president's 'Star Wars' proposal from stardust and moonbeams to that great pork barrel in the sky."