French anti-terrorism prosecutors said on Friday they had opened a preliminary investigation into suspected torture and war crimes over the alleged mistreatment by ‌Israeli authorities of French nationals who were part of an activist flotilla bound for Gaza.

The probe follows Israel’s interception of the flotilla, which the activists said had been ​seeking to deliver humanitarian aid to Gaza ⁠and to challenge Israel’s naval blockade of the ​Palestinian enclave.

The PNAT anti-terrorism prosecutor’s office said it had ​opened the preliminary investigation after a referral from the French foreign ministry on May 28.

The referral was made under Article ​40 of France’s criminal procedure code, which requires ​public officials to report suspected crimes or offences, PNAT said.

The investigation ‌concerns ⁠suspected torture and war crimes, the office said.

Investigations have been entrusted to the OCLCH, France’s central office for combating crimes against humanity and hate crimes, ​PNAT added.

Organisers of ​the flotilla ⁠have said activists were subjected to abuse, with several hospitalised with injuries and ​at least 15 reporting sexual assaults, including ​rape. ⁠The activists have since been released.

Israeli authorities denied the allegations of abuse. Reuters was not able to ⁠verify them ​independently.

Other Western countries, including Canada, ​Germany and Italy, also condemned Israel’s treatment of the activists.