"The foreign ministry has been informed by Israel that it would intervene if the ship Estelle which is flying the Finnish flag tries to break [Israel's] blockade against Gaza from the sea," spokesman Risto Piipponen said on state television on Saturday.

"We told Israel that the Estelle is a civilian vessel and that its crew is made up of civilians," he said. Israel had been asked to act appropriately, he added.

The yacht, which was built in 1922, sailed from Naples, Italy on October 6 as part of the "Freedom Flotilla" movement, in the latest bid to break Israel's blockade.