The French military has also stepped up flights over the area where wreckage of the plane was spotted.

Colonel Laurent Mathiou, Commander of French Air base in Senegal, said, "The mission today is to localize the debris in the position provided by the Brazilians. We have also seen other objects which do not correspond to the ones we are searching for. We have reinforced the unit you saw last night with the arrival of a French army AWACS."

Investigators say finding the "black box" flight data and voice recorders that hold clues to why the plane crashed will be difficult.

French investigators are working to probe various aspects of the case, including a review of the plane's on board systems and maintenance record.

The investigation will have its first report ready by the end of the month.

(CCTV June 4, 2009)