Israel warned on Tuesday that it would block a fleet of nine ships carrying some 700 international pro—Palestinian activists and supplies from reaching the Gaza Strip later this week.

The Freedom Flotilla, organised by the group Free Gaza, is the largest of its kind since Israel and Egypt began their blockade of the Gaza Strip in reaction to the 2007 takeover of the salient’s operation by the Islamist Hamas party.

The blockade has been the source of much international condemnation. Israel argues it is necessary to keep violent elements in the Gaza Strip from rearming themselves with the tools to shoot rockets into Israel.

But the organisers of this year’s protest say they are trying to bring humanitarian goods to the Gaza Strip. Israeli authorities have urged them to bring their goods to the salient via a pre—approved border crossing. Organisers have said no such offer has been made.

Israeli media reported authorities saying the ships — which are sailing from diverse ports in Ireland, Greece and Turkey and are expected on Thursday — would be boarded before they could reach Gaza.

Any activists on board would be arrested.

“Ships that make their own way to Gaza don’t do anything to help the people there,” said Yigal Palmor, a spokesman for the Israeli Foreign Ministry.

A similar, but smaller, action was prevented by Israeli authorities a year ago. Five others have made it to Gaza in recent years.

Mr. Palmor said Free Gaza is “less interested in bringing help, than with advancing their radical agenda, which plays into the hands of Hamas.” This year’s flotilla is populated by a wide range of people, including politicians and artists, many of Palestinian descent.

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