A chartered cargo plane was blocking the runway at Banda Aceh airport, a prime hub for aid to Indonesia's tsunami-hit Aceh province, after its landing gear apparently collapsed.

An eye witness said the Boeing 737 was lying at the end of the runway and leaning on one engine. An Australian soldier on the scene said the plane may have hit a cow.

Helicopters continued to fly in and out of the airport, but planes were not able to land.

A Singaporean soldier said he understood a backlog of planes due to bring in aid was building up in Medan, the largest city on Indonesia's Sumatra island.

Virtually all of Indonesia's confirmed 94,081 deaths from the December 26 earthquake and the tsunami it triggered were in Aceh, which lies on the northern tip of Sumatra, some 1,700 km (1,060 miles) northwest of the capital Jakarta.

Nearly 400,000 Indonesians have been displaced by the disaster and many are in desperate need of food and medical aid.