Black Sea crash wreckage located

A Russian salvage boat has reached the wreckage

The cockpit of a Russian Tu-154 airliner which crashed into the Black Sea has been located, as speculation continues about the causes of the crash.

Distraught relatives gathered in Tel Aviv to wait for news

The plane - flying from Tel Aviv in Israel to the Russian city of Novosibirsk - was carrying 64 passengers and 12 crew, when it apparently exploded in mid-air.

Russian President Vladimir Putin said the plane might have been brought down by terrorists.

But a US official in Washington suggested that the airliner was accidentally hit by a Ukrainian missile fired during a military training exercise near the crash site.

Thirteen bodies have so far been recovered from the crash site, 190km (115 miles) south of the Russian city of Sochi.

The plane, carrying mainly Israelis of Russian origin, disappeared from radar screens at 0945 GMT on Thursday.

Ukrainian denial

The Ukrainian defence ministry denied that its forces had caused the disaster, saying adequate safety precautions had been taken.

They said that all missiles had been accounted for, and that the exercises had only begun an hour-and-a-half after the plane crashed.

Mr Putin said Ukrainian officials had told him that the plane had been out of range of the missiles when it crashed.

"The weapons that were being used during this exercise could not reach the area where our Tu-154 was flying," Mr Putin said.

The exercise was carried out in Crimea, on Cape Onuk, about 250km (160 miles) from the site of the crash. It involved firing surface-to-air missiles at unmanned aircraft.

The Ukrainian defence ministry said the missiles had "self-destruction mechanisms in case they deviated from their course."

Pilot saw crash

An Armenian pilot in a nearby plane reported seeing the Russian airliner explode in mid-air before it crashed.

Israel Airport Authority spokesman Pini Shif said air traffic controllers lost contact with the plane four hours into its flight.

He said there were no indications of any problems before the crash - "so we have no information about what really happened".

Israeli aviation officials say flight 1812 - a regular weekly charter flight from Tel Aviv to the Siberian city of Novosibirsk - went through the same stringent security checks that are carried out on all planes travelling to or from the country.

Mechnical failure

Another theory for the crash is that the plane simply suffered mechanical failure.

The three-engine TU-154 plane belonged to Siberia Airlines, which is based in Novosibirsk.

The BBC's Jonathan Charles says Russian airlines generally have a poorer safety record than their Western counterparts.

A TU-154 crashed in the eastern Russian city of Irkutsk in July, killing all 145 people on board.

That crash - the worst Russian air disaster in many years - was due to pilot error, an investigation concluded.