TRIPOLI, Libya - Libyan government forces shot down two US-built attack helicopters being used by rebel forces in the east of the country, Deputy Foreign Minister Khaled Kaim said on Sunday.

He slammed the international community for allowing rebel forces to operate aircraft despite the existence of a no-fly zone over the country following UN Security Council resolution 1973.

"A clear violation was committed by the rebels to resolution 1973 relating to the no-fly zone. The rebels used two Chinook helicopters and they were shot down" near the eastern oil facilities of Brega, he said.

The report could not be confirmed with the rebels, but journalists in the area did describe seeing at least one attack helicopter apparently flown by rebels in the area on Saturday.

But NATO, which enforces the no-fly zone, said it has been applying it to both sides and on Saturday intercepted a rebel MiG-23 fighter jet and forced it to land.

NATO is also continuing to carry out air strikes against government forces, destroying 17 tanks and damaging nine others, the alliance announced on Saturday.

NATO has destroyed key ammunition stockpiles and armored vehicles in recent air strikes across Libya, while government forces pushed rebels back almost to Ajdabiya.

The rebels had pressed westward halfway to the oil refinery town of Brega, 80 kilometers away before being pushed back toward Ajdabiya on Saturday.

To ease the deteriorating situation, a high-ranking African Union delegation was due in Libya on Sunday to present a blueprint for an end to the current crisis as plans for a new constitution were unveiled by parliament.

African Union mediators on Sunday renewed their appeal for "an immediate end to all hostilities" and proposed a transition period to adopt reforms in the insurrection-hit country.

The panel of five African leaders, headed by Mauritanian President Mohamed Ould Abdel Aziz, decided to go along with a roadmap adopted in March which calls for an end to hostilities, "diligent conveying of humanitarian aid" and "dialogue between the Libyan parties", it said.

AP-AFP