Israeli radio and TV Channel 2 are reporting that Israeli navy ships have stopped and boarded the Rachel Corrie, the Irish ship seeking to run the Gaza blockade.
The ship was boarded at 5.45 a.m local time as they were about 35 miles from their target destination.
There are no reports of injuries or scuffles on board and it is not clear where the Israelis are taking the ship.
Unconfirmed reports had it heading towards the port of Ashdod in Israel.
Five Irish nationals, including Nobel Peace Prize winner Mairead Maguire, are on board the ship.Earlier, the IDF had claimed the"Rachel Corrie" had ignored an invitation to unload its cargo at an Israeli port and chose to continue its trip toward Gaza.
The Israeli Defense Forces stated that despite radioing the ship, its organizers "chose to ignore the invitation to dock at the Ashdod port where the cargo could be unloaded and transferred to the Gaza Strip upon inspection."