The Pentagon is abolishing its crack, super-secret intelligence unit called Task Force 157.

Successful, controversial and extremely secretive, Task Force 157 is the U.S. military's only network of undercover agents and spies operating abroad using commercial and business "cover" for their espionage.

Run by the U.S. Navy for seven years from the ninth floor of an Alexandria, Va., office building, the unit has recently controlled as many as 75 contract agents or "spies for hire" who monitor the key ports of the world, Soviet vessels and the shipment of nuclear weapons. The current commander of the unit is Navy Capt. Darryl A. DeMaris.

One informed government source last week discussed the reasons for abolishing the unit: "The simple truth is that spies are too hot to handle . . .there were too many questionable business deals. They got the job done, but the potential for abuse was too great."

Pentagon and Central Intelligence Agency spokesmen declined comment yesterday, saying that all matters relating to Task Force 157 are still classified.

Other sources maintain that the decision to close the unit reflects a sense of caution that is being applied to all intelligence operations.

Task Force 157 has been involved in some of the most sensitive intelligence missions of the last decade. The unit's top secret communications channel, for example, was used to set up Henry A. Kissinger's secret 1971 visit to China.

The White House at the time considered it more secure from leaks than any such channels run by the CIA.

Former Chairman of the Joint Chiefs of Staff Admiral Thomas H. Moorer confirmed yesterday that he had recommended that Task Force 157 provide the communications channel for Kissinger.

Moorer was critical of the decision to abolish the unit, saying, "I think there have been requirements for this capability in the past and there will be cases in the future."

Task Force 157 was valued in the Pentagon because it was a small, independent intelligence unit that could cut through red tape with speed and secrecy. Some Pentagon officials maintain an important capability is being lost not just to the Navy but to the entire intelligence community.

Following the congressional intelligence investigations, Pentagon officials, however, found they lacked the means to fully control the agents working for the small companies, or "cover" firms, called "proprietaries."

Sources said that numerous "cozy relationships" were discovered between the contract employees and firms selling equipment and supplies to Task Force 157.

The final decision to eliminate Task Force 157 was made last year and was ratified again this year in the Carter administration.

All operations are to cease or be transferred to the CIA or other intelligence agencies by Sept. 30 of this year, the sources said.

The cover for the task force is the Naval Administrative Services Command and Pierce Morgan Associates Inc., which operates as an international maritime consulting firm.

Both have offices on the ninth floor of the Seminary Plaza Professional Building, 4660 Kenmore Ave., Alexandria, Va.

One of Task Force 157's highly classified assignments has been on occasion to monitor nuclear weapons shipments aboard Soviet and other vessels as they pass through strategic shipping lane "choke points," or narrow passages, such as the Strait of Gibraltar.

The unit was involved in drawing up a report in 1973 saying the Soviets had shipped nuclear weapons into Egypt during the October Arab-Israeli war. That classified a report leaked to the news media at the time.

Other Task Force 157 projects have included the assessment of Soviet weapons capabilities for the Strategic Arms Limitation Talks (SALT), communications monitoring, and intelligence gathering for recovery of downed airplanes and sunken ships.

Task Force 157 also has been involved in recruiting foreign espionage agents and infiltrating international maritime unions, the sources said.

The Task Force has had 75 contract employees doing undercover work abroad; 50 of these will be terminated when the unit disbands and the remaining 25 will be offered jobs with other intelligence agencies. The unit also employs 75 military and civilian workers in Alexandria, all of whom will be transferred to other intelligence jobs.

The total operating cost for the unit has been about $5 million a year.

One contract employee for Task Force 157 from 1971-76 was Edwin P. Wilson, an ex-CIA agent. Wilson is currently under investigation by the Justice Department for allegedly selling explosive devices and related material to the Libyan government. In addition, federal authorities are trying to determine if detonating devices made for Wilson were used in last year's bombing murder of former Chilean Ambassador Oriando Letelier.

Wilson has denied any wrongdoing.

In 1975 Wilson approached the Director of Naval Intelligence, then Rear Adm. Bob by R. Inman, with an offer to set up a counterpart to Task Force 157.

In the words of one Pentagon official, Wilson "wanted a bag of money to set up another Task Force 157 that would do the things" that have been criticized by congressional investigators of the intelligence community.

Inman then began an inquiry into Task Force 157 operations.

One informed government source said: "Wilson had connections to the Hill which he mentioned and to retired generals and admirals . . .there is a whole string of consulting firms on K Street, selling, making proposals and deals . . . you did not know exactly what you were getting."

The Inman investigation of Task Force 157 discovered the connections between Task Force 157 contract employees and the firms which supplied material and equipment to the operation.

As part of his duties for Task Force 157, Wilson sold a ship to Iran for about $350,000 supposedly for scientific purposes. In fact, it was an intelligence-gathering ship.

Inman did not discover that Wilson or anyone else profited improperly from their Task Force 157 work.

It was a loose way of doing business, Inman concluded, according to sources, and he decided to abolish the unit. Deputy Secretary of Defense Robert Ellsworth approved the decision in February, 1976, according to a classified memo.