By the CNN Wire Staff
(CNN) -- A convoy of boats carrying food and aid to the Palestinian territory of Gaza in defiance of an Israeli blockade is being shadowed by three Israeli warships, according to one organization participating in the flotilla.
At least one of the six boats in the flotilla have also been contacted by Israel Defense Forces radio, the Free Gaza organization reported on its Twitter page.
"We didn't expect them now," said one tweet about 11 p.m. (4 p.m. ET), adding the participants thought Israeli forces would arrive Monday morning.
Three Israeli navy missile boats left a Haifa naval base just after 9 p.m. (2 p.m. ET) to intercept the flotilla.
