Activists aboard a Canadian ship trying to breach the naval blockade of Gaza were beaten by Israeli troops who intercepted the vessel, protest organizers in Ottawa and Montreal charged Saturday.

Israel has said no one was hurt in its takeover of the Canadian-owned Tahrir and an Irish vessel Friday, but organizers for the group "Canadian Boat to Gaza" claimed otherwise.

"The latest we do know is that people are still being held and at least some were beaten when they refused to voluntarily leave the ship," spokesman Dylan Penner said, adding that his group got the information from an official at the Canadian consulate in Tel Aviv. "We're calling for their immediate release."

The Tahrir, which made a previous failed attempt to reach the blockaded Palestinian territory this summer, was carrying medical aid and activists from nine countries when it was intercepted two days after it set sail from Turkey. Troops sprayed the vessel briefly with a water cannon before they boarded the ship and towed it to the Israeli port of Ashdod, north of Gaza.

The treatment of activists is a sensitive issue because of an Israeli raid on a flotilla in 2010 ended with nine Turkish activists killed.

Israeli officials have said troops took action Friday after repeated calls for the vessels to turn around were ignored, and added that the ships were intercepted peacefully.

However, Penner said he had been told some activists — including David Heap, a Canadian from London, Ont. — were "roughed up" when they refused to leave their vessel. Two other Canadians — Montrealer Ehab Lotayef and Torontonian Karen DeVito — were also aboard the Tahrir, but organizers haven't been able to reach any of the activists directly so far.

"This is very concerning on a whole number of levels," Penner said, adding it was unclear whether the Canadians and others they were with had received adequate medical attention or access to lawyers.

Israeli officials said deportation procedures were underway for 22 activists, who were expected to be sent home within 72 hours. Two Greek crew members were flown home Saturday. Three journalists from the U.S., Spain and Egypt who had been aboard the two ships were also released and told to leave by Sunday.

Israel has said its naval blockade of Gaza, imposed in 2007, is vital to stop weapons reaching the Iran-backed Hamas militants who control the territory. Critics say it amounts to collective punishment.

Israel sees the attempts to break the sea blockade as provocations and publicity stunts. It said the amount of aid in the small boats used by activists is insignificant, as Israel transfers aid to Gaza daily.

But activists have disagreed with that assessment and have said they will attempt to breach the blockade again in the future.

A spokesman for Foreign Affairs Minister John Baird issued a statement Saturday that said Canadian diplomats are closely watching the situation and are "are liaising with Israeli authorities" in order to provide consular assistance. Ottawa has warned Canadians against all travel to Gaza, saying the security situation along the coast remains volatile.

Baird has also said Canada can't protect Canadians who break the laws of another country. He urged those wishing to deliver aid to do so through "established channels."

"Unauthorized efforts to deliver aid are provocative and, ultimately, unhelpful to the people of Gaza," he had said in a statement. Baird also recognized Israel's right to protect itself and its people from attacks by Hamas and other terrorist groups, including through prevention of weapons smuggling.