A union leader has accused a Kiwi diplomat of not offering him proper support while in Israeli detention.

Photo: Supplied / Unite.

Unite leader Mike Treen was detained by Israeli forces while taking part in a flotilla attempting to deliver supplies to Gaza.

Mr Treen is unhappy about the support he received from a New Zealand consulate official.

"He essentially acted as an agent of Israel, not as a protector or advocate," Mr Treen said.

"First of all, he had me, unlike other diplomatic people who went out to meet the people who had been detained and met their people in the private room, he met me in a room with prison and security officials.

"I said I wasn't very happy about it, he said there was no room available. He then implied, when he saw some wounds to my face...he implied that it was my fault. And then he tried to force me to sign a self-deportation order and said I didn't need to see a lawyer.

"The other representatives got to see their property, in the room, that had been seized. I never got to see mine."

Mr Treen said he would be writing a "full detailed report" to send to the Minister of Foreign Affairs.