At a time when Col. Muammar Qaddafi has been seeking increased international respectability, Libya's government-controlled news agency reported today that assassination squads have resumed their attacks on opposition leaders abroad.

The news agency, Jana, said Abdul Hamid Bakoush, the last prime minister under the deposed Libyan king, Idris, was "executed" Monday at 3 p.m. by a "suicide squad" but did not say where the assassination had taken place. Bakoush's secretary, Mahmoud Abul Kheir, told reporters that he had last seen him alive late Monday morning at a meeting at a hotel in downtown Cairo. He had failed to show up for another scheduled meeting later the same day, Abul Kheir said.

Egyptian officials had no immediate comment on the Libyan claim, but Bakoush's house in the suburb of Heliopolis was under unusually heavy guard this afternoon.

If the Libyans have succeeded in kidnaping and executing Bakoush, the event is certain to provoke renewed tension between Libya and Egypt and possibly some kind of Egyptian retaliation.

The incident also has broader implications for several prominent international actors.

The timing of the announcement would appear to be an embarrassment to French President Francois Mitterrand, who met only yesterday with Qaddafi on Crete. Mitterrand is facing growing criticism at home and signs of considerable irritation from Washington for his dealings with the Libyans Details on Page A13 .

Morocco's King Hassan also recently engineered a political detente with the Libyans, contending that it would give him influence over Qaddafi's often troubling international activities as well as support in his campaign against Polisario guerrillas contesting Moroccan control of Western Sahara.

Egyptian President Hosni Mubarak already has accused Libya publicly of being behind the mining of the Red Sea, which caused damage to nearly 20 ships in August and September. He also has claimed that Qaddafi had plans to blow up a ship in the Suez Canal and bomb the Aswan Dam, and he has warned sternly that Egypt would retaliate with force if any attempt to carry out either plan were made.

The Egyptians are not likely to take it lightly now if Qaddafi has managed to slip an assassination team into the heart of Cairo and execute a Libyan opposition leader who was under the protection of the Egyptian government. For one thing, it would show that Libyan agents are still able to infiltrate and operate here, despite stringent security, and could strike at other targets, possibly American ones.

Why Qaddafi decided to single out Bakoush for execution was not immediately clear, unless he deliberately wanted to demonstrate to the Egyptians that he is capable of striking even in downtown Cairo.

Bakoush, who was jailed by Qaddafi but escaped to Egypt, headed a minor Libyan opposition movement, the Organization for the Liberation of Libya, set up here in 1982.

The Libyan news agency said the country's "basic people's congresses" had decided to form "suicide squads to liquidate enemies of the people's authorities inside and outside the country." Libya has been sending assassins abroad to liquidate "enemies of the revolution" for some time, and a score of persons have been killed in various West European capitals.

The Libyan agency went on to say that "revolutionary forces executed the death sentence last Monday, Nov. 12, at 3 p.m. on traitor, agent and stray dog Abdul Hamid Bakoush." It accused him of having "sold his soul to the enemies of the Arab nation . . . who are hatching conspiracies and plots" and promised that Libya's "suicide squads will continue to chase the stray dogs wherever they may be." Bakoush served twice as justice minister in the mid-1960s and then as prime minister starting in 1967. He was jailed by Qaddafi just after he seized power in 1969.