The Australian air crash investigator has slammed a US deep sea search company as unprofessional after it criticized efforts to find MH370 based on a couple of photos.

Seattle based Williamson and Associates, which helped find Air France Flt 447 in 2009, said that images released by the Australian Transport Safety Bureau early in October show a debris field that bears a striking resemblance to the AF447 field.

In a research paper obtained by Reuters Williamson and Associates, which was an unsuccessful tenderer for the MH370 search, said it "believes the target (sonar image) bears the hallmarks of a classic high-impact debris trail similar to other wrecks it has located" and should be investigated further.

However yesterday the ATSB defended its search partner Furgo saying that "based on analysis of all of the data, there are no indications that there is anything possessing the characteristics of an aircraft debris field."

“We consider it unprofessional to draw conclusions based on the limited information provided by the images in the search update report,” the ATSB said.

“We know that this kind of public commentary is very distressing for the families of those on board the aircraft.”

The ATSB said that “the images of the two sonar contacts included in the Operational Search Update released on 1 October were a very small sample of extensive data collected on several passes made at lower altitude, varying range scales and sonar frequencies with the deep tow system on board Fugro Discovery.”

It added that “three separate additional passes were made over the contact.”

The ATSB said that the data was assessed, holistically, by expert geophysicists and sonar data specialists on board the Furgo vessel and independently by its own sonar data quality assurance team.

“Their assessment was made in the context of the adjacent geology and the broader geology found in the search area and it took account of the known characteristics of comparable aircraft debris fields.”

The ATSB said that all the experts are satisfied that the structures are consistent with the surrounding geological formations.

So far 70,000 sq km of the 120,00o sq km area of highest probability has been searched.

Separately the apparent sighting of wreckage of MH370 on the remote island of Sugbay in the Tawi-Tawi chain of islands in the southern Philippines has turned up nothing.