As the investigation into the ill-fated Russian passenger airplane which crashed into the Black Sea last week continues, information implicating Ukraine came to light on Wednesday.

The BBC reported evidence that suggested a Ukrainian missile was involved in the accident. "Many metallic parts were found and are similar to parts of S-200 rocket," said Yevgeny Shaposhnikov, a member of the commission investigating the accident.

The Russian passenger airplane TU-154 (Siberian Airlines), crashed into the Black Sea last Thursday killing all 66 passengers and an 11-member crew. It was flying from Tel Aviv over Turkey to Novosibirsk in Russia.

Zhivko Zhelyazkov, director general of Bulgarian Civil Aviation said at a press conference held on Monday that the plane did not enter Bulgarian airspace. "The plane did not make a stopover at the Bulgarian airport of Bourgas, as some news agencies reported," he added.

According to Zhelyazkov, the plane's fuel tanks were not topped up in Bulgaria, nor were additional passengers allowed to board, as some newspapers had reported.

Russian Federal Security stated shortly after the crash that the cause was likely an explosion onboard the plane. The Russian RIA news agency reported on Thursday that Russian President Vladimir Putin said explosion was probably the result of a terrorist attack.

The crash prompted Israel to suspend all flights from the Tel Aviv airport for three days.

The investigation has revealed that 51 of the passengers onboard were Israeli citizens and the remaining 15 had Russian citizenship. The authorities at Ben Gurion airport in Israel revealed on Thursday that no change of the plane's route had been announced, and there had been no indications of highjackers on board the plane.

Natalia Fileva, deputy director of Siberia Air, said on Tuesday the president of the airline, Viktor Alekseev, had been a passenger on the plane.

Research into the accident is now leading in two directions. One theory is of a terrorist attack, another is that there may have been an accident during a Ukrainian military exercise.

A few hours after the accident the Pentagon in Washington announced that a satellite had detected a land-to-air rocket. Officials from the Ukrainian naval forces announced that they had had military practices and test-fired S-200 type missiles, but finished the training at 1.30pm local time. According to the Russian Interfax news agency, this was approximately 20 minutes before the explosion on the plane occurred.

Ukrainian Defence Minister Oleksandr Kuzmuk denied on Tuesday that a missile was to blame.

The investigation into what caused the accident is still ongoing by Russian and Israeli authorities.