Brazilian Air Force aircraft have detected larger items of debris in their search for the presumed crash location of the missing Air France Airbus A330.

In an update the Brazilian defence ministry says the air force's Embraer R-99 has identified four areas of wreckage about 90km south of the original region being covered by the search aircraft.

The observations included a section debris around 7m (23ft) in diameter, an oil trace stretching to some 20km, and various other objects, including pieces of metal.

Eleven aircraft, operating from Natal and Fernando de Noronha, are being used in the search, among them a US Lockheed P-3 which has recently joined the effort.

A330 search slick
 © Brazilian Air Force

The P-3 and four other aircraft - three Lockheed C-130s and a Dassault Falcon 50 - are conducting flights to verify the R-99 crew's sightings.

Scrutiny of the ocean surface has concentrated on a region some 700km northeast of Fernando de Noronha. Five Brazilian naval vessels are en route to the search area, while three Dutch and French merchant ships have already arrived to aid recovery.

France's air accident investigation agency, Bureau d'Enquetes et d'Analyses (BEA), is taking charge of the inquiry. But it is has warned that it may be forced to work without crucial evidence, given the ocean depth and sub-sea terrain.

Director Paul-Louis Arslanian says the recovery effort faces regions of extremely deep water and a terrain which is "more of mountains than of plains".

He says the inquiry "cannot be satisfied with 80% understanding", but admits that it may have to proceed with the prospect of a full conclusion never becoming known.

Arslanian says that, without the cockpit-voice and flight-data recorders, he would be "pessimistic about reaching established facts". But even if they are retrieved, he says, the BEA "cannot guarantee" that it would be able to go further that it could without them.

Source: Flight International