No new radio signal has been received from an EgyptAir jet since the day it crashed in the Mediterranean last week, according to sources close to the investigation.
Media reports tonight suggested a new signal had allowed officials to further home in on where the black box recorders might be located.
But a source says there has been nothing since the day of the crash, when a radio signal from the plane's emergency locator transmitter allowed officials to determine a broadly defined search zone.
The Airbus A320 plane, which had been travelling between Paris and Cairo, disappeared from radar on 19 May about 16 km after entering Egyptian airspace. There were 66 people were on board.
The transmitter, picked up by satellites in the international search-and-rescue network, turned out to be separate from the underwater locator beacons or "pingers" attached to the flight recorders.
A French warship was taking detectors to the search zone, designed to pick up under pinger signals over distances of up to 5 kilometres.
The plane and its black box recorders have not been located.
Life vests, parts of seats and objects clearly marked EgyptAir were recovered about two days later, with French air investigation agency Le Bureau d'Enquêtes et d'Analyses confirming the flight sent signals that smoke was detected before the plane crashed in the Mediterranean.
Body parts found afterwards showed signs there might have been an explosion on board.
The Egyptian military also released images of the debris.
Initial Greek military reports that the plane swerved wildly were later rejected by Egypt officials.