Activists on the pro-Palestinian ships that aim to block the Israeli blockade on Gaza say two Israeli warships have surrounded the two boats and that they have lost all contact with the world.
The campaign organisers in Canada and the EU tweeted that they lost contact with all journalists onboad and suspect that the Israeli navy jammed the boats' communications.
They also detailed that the boats are about 40 miles off of the Gaza shore, but still in international waters.
An hour earlier (12pm GMT) the Israeli navy made radio contact with one of the ships.
In a statement published on the Canada Boat to Gaza campaign website reads that an Israel navy officer warned the captain that Israeli navy ships would intercept them at any minute.
"At 10:58 am (Irish time) we received an urgent call from Dr. Fintan Lane, National Coordinator of Irish Ship to Gaza aboard the MV Saoirse, to say that two Israeli ships are rapidly approaching the Irish and Canadian boats. The MV Saoirse and Tahrir are 48 nautical miles from Gaza’s shores," said the statement.
"We will keep coming and coming until the blockade of Gaza is lifted" campaign organisers said on the Tahrir boat Twitter page.
They added that Israel has no rights to control any Palestinian sea, land or air. They called on the Canadian government to "protect the ship instead of protecting Israeli brutal policies against aid ships."
Between the two boats, they carry 27 passengers and some $30,000 worth of medical aid, as well as journalists and crew members, said organisers.
The ships left a port in southern Turkey on Wednesday and were expected to reach Gaza by Friday morning.