The Israeli Navy has intercepted a Gaza-bound vessel with activists and forced it to sail to an Israeli port, the military says.
It says it acted in international waters to prevent the “intended breach of the maritime blockade of the Gaza Strip”.
There was no violence as the navy searched the boat, Israel says.
The activists earlier said they were carrying humanitarian aid, including medicine and solar panels for Gaza.
The boat intercepted on Monday is believed to be Marianne – the lead vessel of a four-strong flotilla.
“In accordance with international law, the Israeli Navy advised the vessel several times to change course,” the military said in a statement, the AFP news agency reports.
“Following their refusal the Navy visited and searched the vessel in international waters in order to prevent their intended breach of the maritime blockade of the Gaza Strip.”
The vessel is currently being escorted to the port of Ashdod.
The flotilla is the latest in a number of protest voyages against Israel’s blockade of Gaza, which is run by Hamas militants.
In 2010, nine Turkish activists were killed aboard another activist vessel during an Israeli raid.
Ten Israeli soldiers were injured in the incident on the Turkish-owned ship Mavi Marmara as it attempted to breach the Gaza blockade.
It caused a deep rift between Israel and Turkey, who were former allies.
