The anti-Gaza war Freedom Flotilla Coalition (FFC) says Israeli troops boarded a boat that was trying to bring food aid to the Gaza Strip by sea, BBC reported.

It said the Handala vessel was intercepted in international waters.

Video footage purportedly showed activists on board with their hands up as several armed soldiers took control of the vessel.

The Israeli foreign ministry claimed that its navy stopped the boat "from illegally entering the maritime zone of the coast of Gaza" and breaking the blockade there.

Meanwhile, the FFC said Handala's crew of 19 activists and two journalists from various countries - including Australia, France, the UK and the US - had been "kidnapped" by Israeli soldiers.

The group also posted a number of videos with crew members urging people around the world to put pressure on their respective governments to "sanction" Israel.

The boat was carrying baby formula to Gaza, one of the FFC activists said in a post on social media.

In June, a yacht with 12 activists on board - including Sweden's Greta Thunberg - was intercepted by the Israeli military about 185km (115 miles) west of Gaza.

That expedition, also organized by the FFC, had been aiming to deliver aid to Gaza in defiance of Israel's blockade and to highlight the humanitarian crisis there.

At the time, the Israeli foreign ministry claimed it was a "selfie yacht" carrying "less than a single truckload of aid". 

Israel stopped all deliveries of humanitarian aid and commercial supplies to Gaza on March 2 and resumed its military offensive two weeks later, collapsing a two-month ceasefire with Hamas.

Israel has since been prioritizing aid distribution through the Gaza Humanitarian Foundation, which is backed by the US.

The UN and other aid groups are refusing to cooperate with the new system, saying it contravenes the humanitarian principles of neutrality, impartiality, and independence.