Hillary Clinton has condemned the pro-Palestinian activists who plan on sailing a flotilla to Gaza as unhelpful and provocative.

The US Secretary of State said the plans, which would see a flotilla departing later this month with the intention of breaching Israel's sea blockade of Gaza, would only serve to increase tensions in the region.

"We do not believe the flotilla is a necessary or useful effort to try to assist the people of Gaza," said Mrs Clinton.

"It's not helpful for there to be flotillas that try to provoke action by entering into Israeli waters and creating a situation in which the Israelis have the right to defend themselves."

Her comments followed a State Department warning to the 36 American participants in the flotilla that Gaza was "dangerous and volatile". They said no attempt should be made to travel there.