Greek authorities intercepted late on Monday a second ship from the Freedom Flotilla II during an attempt to break through Israel's blockade of Gaza.
The Canadian vessel Tahrir, which carried supplies and a group of pro-Palestinian activists on board, tried to leave Greek territorial waters without permission. The ship was boarded by Greek coastguard officers and ordered to stop the engines.
"The ship has been towed back to the port of Agios Nicolaos [on Crete]," a spokesperson for Greek coastguard said, adding that no casualties among the passengers had been reported.
Israel cut off access to the Gaza Strip in the middle of 2006 after Palestinian Islamists abducted Israeli serviceman Gilad Shalit. Israel has since threatened to thwart any attempts to approach the enclave from sea and urged humanitarian vessels to unload their aid at other ports.
Human rights and pro-Palestinian activists have been campaigning to end the blockade and attempting to send humanitarian aid to the enclave for years.
Last week, Greek authorities intercepted another of at least 10 ships in the flotilla, the Audacity of Hope, for making an attempt to illegally set sail for the Gaza Strip.
In May 2010, Israeli commandos seized control of a Turkish vessel, the Mavi Marmara, which was part of the first Freedom Flotilla. Nine activists died in the raid near the Gaza coast, with each side blaming the other for the fatalities.