UNITED NATIONS (AP) _ An official responsible for U.N. famine relief efforts in the Sudan said Monday that ''Operation Rainbow'' flights were suspended because of increasing attacks on aircraft flying over southern Sudan.

Winston Prattley, the U.N. secretary-general's special representative for relief operations in the Sudan, also said a Sudanese government plane apparently carrying food was hit by ground fire.

He said Operation Rainbow flights had delivered 300 tons of emergency supplies in the five days they were able to operate.

The U.N. operation was ordered suspended on Friday last week because ''targeting of aircraft trying to use these (south Sudan) air fields has been stepped up,'' he said.

No Operation Rainbow planes have been hit, but Prattley said in ''the last 24 hours there has been another incident in the vicinity of Juba. An aircraft was hit.''

He did not give any details other than to indicate the plane was a Sudanese government plane, apparently was just damaged, and, ''I was told it was carrying food.'' The Sudanese government said nothing about one of its planes being hit.

Juba, the main city in southern Sudan, is held by the government. The Sudan People's Liberation Army, which has been fighting the government since 1983, had threatened to shoot down any plane that flies over the territory they hold without their permission.

In August, the guerrillas downed a Sudanese airliner, killing all 60 people aboard. The guerrillas claim the government uses civilian aircraft to reinforce its troops. Operation Rainbow organizers said the would guarantee that their flights were only for food and medical relief.

Operation Rainbow was projected as a 30-day operation to bring in $980,000 worth of food to airfields in the towns of Malakal, Wau and Juba. But the airlift lasted only five days, with a chartered French DC-8 and a Australian C-130 Hercules flying in 300 tons of supplies.

Prattley said that ''was not very much in terms of total need.''

The operation was started by a consortium including the World Food Program, the U.N. Children's Fund, the United States, Canada, France, the Netherlands and Ireland.

The DC-8 was preparing to leave Khartoum, the Sudanese capital, with more supplies Friday when the decision was reached to suspend the flights. Mother Teresa, the Roman Catholic nun who won the 1979 Nobel Peace Prize for her work with the needy, was aboard the DC-8.

The plane returned to France and the Hercules was at Larnaca, Cyprus, awaiting developments.

Prattley said efforts are being made to get food into the south by road from neighboring Uganda, Kenya and Zaire and to set up temporary relief camps at strategic locations on the edge of the embattled region.

He said the United Nations hoped to encourage new attempts at bringing supplies down the Nile by barge but was finding ''no enthusiasm'' from barge operators or crews.

In Khartoum on Monday, the official Sudan news agency quoted Mohamed Kamil Shawki, Sudan's relief director, as saying the national carrier Sudan Airways chartered an aircraft on Monday with cooperation of some unidentified foreign relief organizations to ferry supplies to Juba. He gave no further details.

The news agency also said that SPLA guerrillas overran the village of Lanya, 62 miles south of Juba, and killed nine soldiers. The news agency said the village is on a road used by Operation Rainbow trucks ferrying supplies from Zaire to Juba.

The news agency said government troops had later secured the road to allow safe passage of relief trucks.

Operation Rainbow began Oct. 12 after a three-week delay due to threats by the guerrillas to shoot down the operation's aircraft unless it alternated between rebel and government-controlled areas.