Marine Lt. Col. William Higgins, who was kidnaped last week by Shiite extremists in southern Lebanon, may have attracted attention to himself by letting it be known widely there that he had previously worked for former secretary of defense Caspar W. Weinberger, according to Arab diplomatic and other sources close to the U.N. operation there.

The sources said that Higgins had let it be known among his colleagues on the U.N. Truce Supervision Organization (UNTSO) and others with whom he came into contact in southern Lebanon that he had served as an aide to Weinberger.

"Higgins presented himself as a sort of super envoy, as Cap Weinberger's envoy," said one source close to UNTSO who added, "He came across as a bit of a cowboy."

Both the Christian-run Radio Free Lebanon in Beirut and Radio Israel have carried reports about Higgins telling of his former association with Weinberger.

The Organization for the Oppressed on Earth has asserted responsibility for the kidnaping, and called Higgins an agent for the Central Intelligence Agency. The Reagan administration has strongly denied this.

Yesterday, Higgins' captors released a 70-second videotape in which the career Marine was shown reading demands of the organization, which included release of prisoners in Israel and a halt to "U.S. intervention" in the Middle East.

"Obviously, it was made under duress," White House spokesman Marlin Fitzwater told reporters. "We continue to call for the immediate and safe release of Col. Higgins, as well as other hostages in Lebanon."

Higgins, 43, served as the junior military assistant to Weinberger from June 1985 until he was assigned to the U.N. post last June. He performed a wide variety of administrative duties in the Pentagon, but never held a senior-level job.

U.S. and Arab sources suggested that Higgins' past position as a Weinberger aide may explain why he attracted the attention of the radical Shiite group, Hezbollah (Party of God), which is believed to be behind his kidnaping south of Tyre last Wednesday. The Organization for the Oppressed on Earth is believed connected to Hezbollah.

The U.S. and Arab sources suggested that another possible reason for the kidnaping may have been Hezbollah's hatred of all U.N. peace-keeping forces in southern Lebanon, where the radical Shiite group is in sharp competition with the more moderate Shiite Amal organization, which supports the U.N. presence.

Hezbollah in February 1985 published a "manifesto" attacking the 5,800-man U.N. Interim Force in Lebanon (UNIFIL), which has served since 1978 as a source of Western influence and spies in the country. In late 1986, Hezbollah carried out attacks on members of UNIFIL's French contingent. Four French soldiers died, and France sharply reduced its troop commitment.

"Hezbollah wants UNIFIL out of southern Lebanon," said one Arab diplomat here who added that the Higgins kidnaping may have been an indirect way of getting at the U.N. presence.

UNIFIL is also in serious difficulty because the United States, which normally contributes a third of its operating costs, has fallen far short in its contribution the past two years. As of last April, the United States was $60 million in arrears.

Higgins, according to various sources, was a highly ambitious officer who actively volunteered for the job as head of UNTSO's 75-man Lebanon Observer Group and hoped to use it as a springboard to senior rank. He had spent most of the past seven years in Pentagon assignments, and experience in peace-keeping roles abroad is widely regarded within the U.S. military as one road to success.

Defense Department officials said the assignment offered him a chance to lead a multinational force in one of the few "hot spots" during peacetime for the United States.

"He's gung-ho," said one acquaintance. "He wants to be commandant of the Marine Corps."

Many Pentagon and State Department officials now concede it may have been a poor decision to send Higgins to Lebanon directly from his assignment in Weinberger's office.

But others noted that all 36 UNTSO positions allotted to Americans are highly coveted among ambitious U.S. officers who scramble to jockey for such assignments and usually have all served in potentially sensitive or high-level jobs prior to winning one.

"We wouldn't have sent a guy over there who hadn't served in one of those jobs," said one knowledgeable source. "We'd never send a turkey."

Higgins had worked as a project officer for the defense secretary's Annual Report to the Congress, a volume setting out the military's needs and strategies for the coming year. He served in a similar position at the Marine Corps headquarters, preparing the services's annual plans and posture statement.

He has also studied at the National War College and the Air Force Command and Staff College.