The free-ranging Lebanese force commanded by Saad Haddad and equipped by Israel has been shooting at Norwegian troops and cutting off their food supplies in a dispute over the role of the United Nations Interim Force in Lebanon (UNIFIL), Norwegian officials said yesterday.

A Norwegian official, who declined to be quoted by name, said confrontations between Haddad's soldiers and the Norwegian infantry brigade assigned to the U.N. force have been occurring for the past two weeks in southeastern Lebanon, including gunfire but no casualties.

This newest squall breaking over already stormy Lebanon revolves around whether Haddad's armed troops should be allowed to pass freely through Norway's newly expanded area of operations in the easternmost part of the country on the Israeli border. Norway recently took over from Nepalese troops, who, sources said, allowed Haddad's men free passage.

"We have been following the U.N. rules which say armed men in uniforms should not be allowed to pass through," said a Norwegian official in explaining why his country stopped Haddad's forces. Haddad's army totals about 2,000 and has been supported by Israel since 1978 as a surrogate to help control southern Lebanon. Haddad is a cashiered Lebanese army major.

After Norwegian infantrymen tried to keep their area from being used as a corridor, Norwegian officials said, Haddad's forces surrounded six Norwegian infantry trucks and jeeps, and shot at the feet of the soldiers in them until they abandoned the vehicles. Then, the Norwegians said, Haddad's men drove off in the vehicles.

Besides that, the Norwegian officials continued, Haddad's soldiers refused to allow Norwegians to take food and water to isolated Norwegian observation posts of two or three men. After intense negotiations, Haddad allowed French personnel within UNIFIL to supply the Norwegian outposts, the officials said.

Other harassment included refusal by Haddad's forces to let about 100 Norwegians coming off leave in Israel return to their battalion's position in eastern Lebanon. Norway, in response to this, flew its soldiers over Haddad's roadblock by helicopter.

"We were very upset about it," said a Norwegian official in discussing the harassment. He added that negotiations are under way to resolve the problems of Norway's battalion of 648 men in the 6,500-member UNIFIL force designed to provide a buffer between Lebanon and Israel.

The Israeli government has complained that UNIFIL has failed to keep southernmost Lebanon clear of Palestinian combatants, who have shelled northernmost Israel and launched terrorist raids from there. Given that record, Israel has opposed enlarging UNIFIL's peacekeeping role in Lebanon.

Haddad's challenges to Norway over the last two weeks provide a fresh test of strength for UNIFIL. The 1,200 U.S. Marines now trying to help stabilize Beirut and its environs are part of a separate outfit known as the multinational force because it consists of American, Italian and French troops. The Reagan administration is considering an expansion of the 3,800-man multinational force, both in numbers and responsibilities.

The Marines have already started patrolling by jeep the first, in-city, part of the Beirut-to-Damascus Highway. The Pentagon has mapped plans to extend this patrolling out from the city, with the timing depending on how fast Israeli and Syrian troops withdraw from the highway's corridor, officials said.