Amnesty International have dismissed as “a whitewash,” a report into the clash on the Gaza-bound flotilla last year which found that Israel was acting in self-defence.

The organisation criticised the Turkel Commission panel for using “highly contentious legal arguments” in its research and for failing to explain the causes of the deaths of nine Turkish pro-Palestinian activists on board the Mavi Marmara.

The probe, which was conducted independently and overseen by the former Northern Ireland First Minister David Trimble, has been praised by the US State Department as “credible, impartial and transparent”.

Among the findings of the Turkel Commission were that the activists, who had claimed to be on a peaceful mission, had no humanitarian aid supplies with them but were carrying knives.

Photographs from the Mavi Marmara have also shown that there were weapons on board while Sefik Dinc, a Turkish journalist who was on board the flotilla, told Israeli media last year that the soldiers only began firing when they were met by armed resistance in the form of metal truncheons.

However, Amnesty disputed the claim that the activists had used firearms against Israel, arguing that there was no evidence of ballistic tests being conducted “to determine the source of the wounds”.

The Amnesty report cited findings by the International Fact-Finding Mission that alleged the flotilla activists “were posing no live threat to Israeli soldiers” and accused the IDF of using excessive force.

Amnesty said it rejected the conclusions of the report and criticised the Israeli investigators for making insufficient efforts “to obtain additional evidence and testimonies”.

The seven-month investigation included interviews with IDF chief of staff Gabi Ashkenazi and other key figures in the operation. The commission also extended an invitation to Turkish citizens who were on board the Marmara to travel to Israel and testify.