More than 50 European activists have succeeded in breaching the checks at the International Airport of Tel Aviv Ben and on Saturday crossed into the West Bank as part of a pro-Palestinian rally, WAFA news agency said.
The activists aim to take part in the "Welcome to Palestine" campaign - a peaceful mission to visit Palestinian families, which some have called the "flytilla".
The "flytilla" took place as Greece prevented from sailing to the Gaza Strip a flotilla of ships bidding to break the Israeli blockade on the Palestinian territory.
Israeli officials said that by notifying foreign airlines of ticket-holders who would not be admitted to Israel they had prevented hundreds from boarding at their ports of departure.
On Friday Israeli police detained about 120 pro-Palestinian activists who had managed to arrive on flights to the country. They are now being held in Israeli jails and soon will be expelled, the country's immigration service said.