Around 30 boats from a pro-Palestinian flotilla were still sailing toward Gaza on Thursday after the Israeli navy intercepted 13 others, the group behind the effort said.

The Global Sumud Flotilla said on its Telegram channel that the remaining vessels were within 46 nautical miles of the enclave early on Thursday. The flotilla originally set out with about 40 boats aiming to deliver humanitarian aid.

Israel, which maintains a naval blockade on Gaza, began stopping the vessels when they reached about 70 nautical miles offshore, according to the group. Those on board the seized boats have been taken to an Israeli port.

The flotilla says its mission is to bring humanitarian supplies to Gaza, where living conditions have deteriorated sharply during Israel's war with Hamas.

Israel says the blockade, in place for more than 15 years, is intended to prevent weapons from reaching Hamas, the Islamist group that governs Gaza. Aid agencies have repeatedly called for greater access to the territory's 2.3 million residents.