After carrying out a simulation of the crash, the country's security chief said that a Ukrainian missile fired during military exercises may have veered off course and hit the Sibir Airlines Tu-154 because of reflections from the water's surface.

Ukrainian prosecutors and military officials on Thursday reconstructed the moment of impact using a computer and a real Tu-154 flying the same route at the same time as the ill-fated aircraft.

No real missiles were involved during the experiment, which confirmed that the missile could have brought down the plane.

"The mock target was hit twice during computer simulations," said Ukraine's Security and Defence Council chief, Yevhen Marchuk.

He said there was "passive noise" on the radar screens caused by a reflection from the water's surface.

"It is not excluded that this was one of the causes for the missile's homing system losing its target," Mr Marchuk said.

The operation was monitored by Russian and Ukrainian investigators, who were hoping it would help shed more light on what happened.

Ukrainian media said Russia was also investigating whether it played any role in the disaster, since the missile was fired from a Russian military training ground.

Kuchma's measures

Initially, terrorism was suspected as causing the crash, but the finger of blame was quickly pointed at Ukraine's military which was carrying out live missile exercises on the Crimean peninsula, about 200 kilometres (125 miles) away.

Ukrainian President Leonid Kuchma sacked his Defence Minister, Oleksandr Kuzmuk, and some of his officials.

Mr Kuchma ordered a check of all Ukrainian missiles and banned missile launches until the investigation is concluded.

Ukraine has also promised compensation to the families of the 78 victims, most of whom were recent Russian emigrants to Israel.