Three more U.S. marines were wounded after sunset tonight when a 120mm mortar shell landed near the maintenance area in their compound around Beirut International Airport.

About a dozen other shells fell nearby, outside the compound.

Two of the marines were evacuated to the naval ship Iwo Jima, off the coast here, one for treatment of shrapnel wounds in his left hand, the other for a dislocated shoulder. The third marine sustained only minor injuries and was treated on base and returned to duty.

The mortar barrage tonight followed sporadic shelling and small arms clashes late yesterday and early this morning. Marines returned the small arms fire yesterday and earlier today but there were no reports that they did so tonight.

Meanwhile, Lebanese Army spokesmen said they had repelled another attack last night on the town of Suq al Gharb, a key strategic position in hills overlooking the presidential palace, which would afford Moslem Druze militiamen and their allies the ability to fire at point-blank range around the capital.

Druze spokesmen announced today their forces had taken 80 percent of the terrain in the mountains during two weeks of fighting.

There were reports, however, that Christian Phalangist militiamen were reinforcing at their last major redoubt along the coastline south of the town of Damur.

The International Committee of the Red Cross announced it had recovered the body of Clark Todd, 38, the London bureau chief of Canadian Television News in the town of Kfar Matta in the Chouf mountains southeast of Beirut. Todd was wounded in the chest by shrapnel and left behind nine days ago by ABC television crewmen with whom he was working after they were caught in the shelling and fighting that followed the Israeli departure from the mountains.