Cairo, Egypt - A humanitarian boat bound for Gaza, with 12 activists on board – including Swedish climate campaigner Greta Thunberg – will continue its journey "until the last minute", campaigners said on Sunday, after Israel ordered its military to block the vessel.

"We'll stay mobilized until the last minute – until Israel cuts the internet and networks," European parliament member Rima Hassan told AFP from the boat – named Madleen.

The Madleen, part of the Freedom Flotilla Coalition, left Sicily last week with a cargo of relief supplies to "break Israel's blockade on Gaza," where the war Israel's unrelenting assault has entered its 21st month.

"There are twelve of us civilians on board. We are not armed. There is only humanitarian aid," Hassan said.

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Earlier in the day, Israel's defense minister Israel Katz ordered the military to block the boat from reaching the Palestinian territory.

"I say clearly: turn back because you will not reach Gaza," Katz said in a statement from his office.

The coalition responded in a statement on X, saying it expected "interception and an attack from Israel at any moment" and calling for the governments of those on board to protect them.

Nationals of Germany, France, Brazil, Turkey, Sweden, Spain, and the Netherlands are on the boat.

"We're not scared of them," said German human rights activist Yasemin Acar, also aboard.

"The message they have been sending us – that we cannot come closer – is not making us step back," she added.

French MEP Hassan voiced concern over the lack of official response from countries whose citizens are part of the crew.

"No state has responded. The message being sent is that Israel is being allowed to act with impunity, without any guarantee of protection for us," she added.

On Saturday, French Minister for Foreign Trade and French Nationals Abroad Laurent Saint-Martin said that France was obliged to ensure "consular protection" for its nationals aboard the Madleen.

"The six French citizens on this boat are entitled to consular protection," he told a state TV channel.