Nine Indonesians among global activists detained while trying to take aid to Gaza in May filed a complaint against Israeli Prime Minister Benjamin Netanyahu on Wednesday alleging crimes against humanity, their lawyer told AFP.

The men were part of the Global Sumud Flotilla intercepted by Israel and detained along with more than 400 other activists, some for days.

The group asked Indonesia's Attorney General on Wednesday to investigate Israel for offences including piracy at sea and crimes against humanity, lawyer Kafin Muhammad said.

"We are asking the Attorney General of the Republic of Indonesia to conduct an investigation into crimes allegedly committed by Zionist Israel," he told AFP.

Indonesia's criminal code gives the country's courts "universal jurisdiction" over cases that involve crimes committed beyond the country's borders, he said. 

The complaint mentioned Netanyahu by name as Israel's commander-in-chief, Kafin said.

It includes testimony from the volunteers about abuses they claim to have suffered during their detention by Israeli authorities, he said.

A spokesman for the Attorney General's office did not reply to an AFP request for comment.

Israel's treatment of the flotilla activists sparked an international outcry after an Israeli minister posted a video of the volunteers, who were made to kneel with their hands tied behind their backs.

Countries including France, Italy and Australia have opened judicial investigations.

Israel controls all entry points into Gaza, under blockade since 2007.