Ukrainian Prime Minister Anatoly Kinakh was quoted as saying that the theory that his country accidentally shot down a Russian airliner had a right to exist.
Asked to clarify the report, Mr Kinakh's spokesman said: "The prime minister said there were several theories and they all have a right to exist and it's too early to draw any conclusions because an investigation is under way."
It was the first statement by a senior Ukrainian official conceding any possibility that exercises with long-range surface-to-air missiles on the Crimean peninsula might have caused the mid-air explosion of the Sibir airlines flight from Tel Aviv to Siberia.
Ukraine's Defence Ministry has denied that any of its missiles could have struck the Russian Tu-154 yesterday, but officials in Washington have said there was every indication the Ukrainians shot the plane down by accident.