Ukrainian Defence Minister Mr Olexander Kuzmuk said today he hoped to prove his military did not shoot down a Russian airliner last week, killing 78 people.
The former Soviet state has come under increasing pressure to prove that one of its missiles did not accidentally lock on to a Sibir airlines Tu-154 jet that exploded over the Black Sea during Ukrainian military exercises last Thursday.
Ukraine has denied involvement, but US officials say they saw a rocket plume on a spy satellite image of the crash area.
Russia's Interfax news agency quoted unnamed investigators today as saying they had found what appeared to be shrapnel from an anti-aircraft missile among the aircraft's wreckage.
The Ukrainian military said it launched an S200 anti-aircraft missile at about the time the Russian airliner exploded in mid-air, but it maintains the Ukrainian missile crashed into the sea up to 200 kilometres (125 miles) from where the aircraft came down.
But Russian President Mr Vladimir Putin was quoted as saying at the weekend that he was unhappy with the information Ukraine had provided so far.
If the Ukrainians can prove their missile landed well short of the airliner, speculation will revert to a bomb or catastrophic mechanical failure on the aircraft, which was flying from Tel Aviv to Siberia.