Israeli forces have started seizing aid vessels headed for Gaza in waters far from the country's coastline, Israeli media reported Thursday, drawing condemnation from Hamas, which described the move as "piracy."

According to Israel's state-run Army Radio, the navy had moved to intercept a humanitarian flotilla, though it did not disclose further operational details.

Israeli Foreign Ministry spokesperson Oren Marmorstein posted video footage purportedly filmed aboard one of the vessels, alleging that drugs had been discovered on board.

The spokesperson did not clarify how many ships were intercepted or where the operation occurred.

The flotilla was reportedly intercepted near the Greek island of Crete, several hundred nautical miles from Israel. Israeli naval forces had previously intercepted vessels from the flotilla in waters closer to the Gaza coast.

The convoy, carrying humanitarian supplies intended for Palestinians in the war-ravaged Gaza Strip, set sail from Barcelona, Spain, on April 12 in an effort to challenge Israel's blockade of the enclave.

Senior Hamas official Osama Hamdan denounced the interception, calling it "an act of piracy" and a violation of international law.