Israel is seeking to deport 21 pro-Palestinian activists from 10 countries who were detained after their Gaza-bound boat, the Handala, was intercepted by the Israeli navy in international waters on Saturday.

The activists, from the Freedom Flotilla Coalition (FFC), were brought to Israel's Ashdod port and are being held under immigration law, despite being forcibly taken from international waters. Adalah, a legal aid center, reports that Israeli authorities offered them a choice: "voluntary deportation" or continued detention and a tribunal hearing.

Three activists, including French MP Gabrielle Cathala, have agreed to deportation. Twelve, including French MP Emma Fourreau, have refused and remain in custody. Two Al Jazeera journalists and two dual US-Israeli nationals were also among those detained; the latter were released after interrogation.

Adalah maintains the mission was "peaceful" and both the detention and Israeli blockade of Gaza are illegal. The Israeli foreign ministry stated the navy intercepted the Handala to prevent it from "illegally entering the maritime zone of the coast of Gaza" and that all passengers are safe. A previous FFC boat, the Madleen, carrying activists including Greta Thunberg, was also intercepted in June and its occupants eventually expelled.