Polish researchers laid some conspiracy theories to rest Thursday and said World War II General Wladyslaw Sikorski died from multi-organ injuries after a plane crash.

Sikorski suffered injuries to his skull, broken ribs and serious injuries to his spine, researchers said, when his Royal Air Force plane crashed into the sea in July 1943.

The findings put to rest some speculation that Sikorski might have been strangled or shot in an assassination plot.

"Nothing goes against accepting that this happened during a flight catastrophe," said Tomasz Konopka, a doctor who presented the findings.

Lead by the Institute of National Remembrance, a probe was launched in November aimed at determining whether Sikorski's death was an accident or possible Soviet-planned assassination.

The general's coffin was taken out of its sarcophagus in Krakow, and was later transported for DNA and medical tests.

Sikorski was a Polish leader and statesman who lead the country's government-in-exile during World War II.

A British report ruled the crash was an accident, but the tense political situation of the time gave rise to a slew of speculation.

No post-mortem had been done until researchers exhumed the body on November 25. (dpa)