Chebeya's brother said the autopsy, carried out by Dutch doctors, confirmed that he had been murdered. His widow called for an international inquiry into his death.

Chebeya, 41, was found dead with his hands tied behind his back on June 2.

The autopsy, carried out by the doctors on June 11, noted superficial cuts and some bleeding around the wrists, forearms and the legs caused by an external source, the family said.

These lesions were "the consequence of applying an external constraint by clamping, compression or shock", such as a tight knot, "blows, collisions or other forms of mechanical stress", it added.

But the autopsy, a copy of which was seen by AFP, said that these injuries had not played a major role in Chebeya's death.

The report did not produce evidence giving a clear anatomical explanation for his death, but said: "The observations are nevertheless strongly in favour of a primary cause of death involving the heart."

The Dutch embassy in Kinshasa handed over the report to his family on Thursday.

"The autopsy proves that the death of Floribert was caused by external actions," his brother Fidele Chebeya told reporters.

"That reinforces what we already thought. He was killed, we are talking about a killing by torture carried out by professionals," he added.

"Now we want to know what really happened," Chebeya's widow, Annie Mangbenga, said.

"For that, we are going to have to have an independent, impartial, transparent inquiry with specialists from abroad, as they did for the autopsy."

Chebeya and his driver disappeared while travelling to the police headquarters, where he had been called to a meeting with police chief John Numbi.

His body was found on the morning of June 2, tied up on the back seat of his car on a road on the outskirts of Kinshasa. The driver, Fidele Bazana, has not been found.

Nearly a thousand people, including foreign diplomats and government ministers attended last month's funeral for Chebeya, who was the president of La Voix des Sans-Voix (The Voice of the Voiceless).

His death had already prompted international criticism, notably from the United States and the European Union.