"The objects are relatively indistinct. The indication to me is of objects that are of a reasonable size and probably awash with water and bobbing up and down over the surface," said Australian Maritime Safety Authority official John Young.

"The largest... was assessed as being 24 metres. There is another one that is smaller than that."

The objects sighted form "probably the best lead we have", Australian official said.

"This is a lead, it is probably the best lead we have right now. But we need to get there, find them, see them, assess them, to know whether it's really meaningful or not," Young added.

NJF/NJF