KHARTOUM, Sudan (AP) _ A Sudanese passenger plane was hijacked today shortly after takeoff but all 36 passengers and crew on board were freed after the plane landed at Port Sudan, the government said.

The official news agency SUNA quoted aviation sources as saying a man and a woman who seized the Sudan Airways plane were demanding the Fokker aircraft be refueled and flown to Cairo. It was not clear who would pilot the plane.

The unidentified hijackers took over the plane after it left Khartoum on a domestic flight to Merowe, about 210 miles to the northwest, SUNA said. It did not say what arms the couple carried.

The two demanded they be flown to Cairo, but the pilot convinced them that he did not have enough fuel and landed instead in Port Sudan on the Red Sea coast, SUNA reported.

Port Sudan is about 420 miles northeast of Khartoum.

The 33 passengers and three crew members were allowed to leave the craft at Port Sudan, while the hijackers remained on board and negotiated with government officials, the agency said.

No motive for the hijacking was reported. Sudan has been involved in a civil war for the past 11 years between the Muslim fundamentalist government in Khartoum and Christian and animist rebels in the south.

Last year, a Sudanese man hijacked a plane on a domestic flight, claiming he wanted to highlight the tragedy of the Sudanese people who have been under military rule since 1989.

In that April 6 incident, Adel Mahmoud Hussen, 26, seized the Sudan Airways passenger plane by threatening the crew with a pistol and knife. He forced it to land at the Egyptian resort of Luxor then surrendered to police. None of the plane's 99 passengers and crew were hunt.

Hussein pleaded guilty and was sentenced to 15 years in prison this week by an Egyptian court.