Kayakers take to water in solidarity with Gaza flotilla

A fleet of yellow, inflatable kayaks has traversed the Sydney Harbour in solidarity with a Gaza aid flotilla intercepted by Israeli defence forces.

Protesters also paddled out in Newcastle in a show of support for Palestinians and the Global Sumud Flotilla, which was attempting to break Israel's naval blockade to deliver supplies to the war-torn enclave.

Six Australians were among more than 700 people on flotilla vessels detained by the Israeli military.

They have since been released on the Greek island of Crete following reports of mistreatment, including activists being hit with rifle butts and shot with rubber bullets.

Israel's foreign affairs minister Gideon Sa'ar insisted participants were not harmed after the vessels were intercepted.

Two Palestinian leaders of the aid mission have been taken to Israel and are yet to be released.

Roughly 40 kayakers took to Sydney's busy harbour on Sunday to express support for the flotilla and participants, paddling from Kirribilli to the Man O'War Steps near the Sydney Opera House.

Rising Tide's Emily Mitchell, who helped organise the paddle protest, said the flotilla vessels were captured far from Israeli territorial waters and outside the nation's jurisdiction.

"This mission is entirely legal and so we demand the Australian government condemns Israel and cuts ties with Israel," she told AAP.

Protesters also paddled out in Newcastle Harbour, including the parents of flotilla detainee, Zack Schofield.

His mother, Joanne Jaworowski, said her son only had a few moments on a borrowed phone to check in to tell them he was in hospital for medical review.

"He shouldn't have to do this," she said.

"Our government should be escorting boatloads of aid to Gaza shores, overland through Egypt and Jordan, breaking the illegal blockade of food and medicine with our true international allies."

Israel controls access to the Gaza strip but denies withholding supplies for the region's two million residents.

The Department of Foreign Affairs and Trade previously said consular officials in Crete were providing assistance to Australians there as part of the flotilla.

It urged Australians not to join attempts to break the Israeli naval blockade of Gaza as they would put "themselves and others at risk of injury, death, arrest or deportation".