澳官员：失踪客机搜寻行动可能会旷日持久

An Australian official has warned that the search for a missing Malaysia Airlines plane "could drag on for a long time" as crews continue to try to find any trace of the aircraft more than three weeks after it vanished.

Former defense chief Angus Houston, who is leading a new joint coordination agency, said 10 military aircraft are working Tuesday searching an area in the Indian Ocean described as the size of Ireland.  He said the task has been difficult because the last known location of the plane is far from where it appears to have gone.

He said the search was the most challenging he has seen, and that so far search crews have not found anything connected to the plane that went missing March 8 with 239 people on board.

Malaysian Prime Minister Najib Razak is due to travel to Australia on Wednesday.