European airlines have cancelled tickets for an unspecified number of passengers planning to attend a pro-Palestinian activist gathering after Israel raised objections.
French carrier Air France and British low fares airline Jet2.com said Saturday they had joined Germany's Lufthansa in cancelling seats on flights to Tel Aviv.
Israeli security forces last week began bracing for a "fly-in" of hundreds of pro-Palestinian activists expected to arrive at Ben Gurion airport outside Tel Aviv this weekend.
The activists, mainly from European countries, are expected to openly declare their intention to visit the Palestinian West Bank, but Israel vowed to prevent them even from arriving.
Israeli Prime Minister Benjamin Netanyahu on Saturday advised activists to concentrate on solving "real problems" in the region, such as Syria and Iran.
"We appreciate your choosing to make Israel the object of your humanitarian concerns," he said in an open letter issued by the prime minister's office.
"We know there were many other worthy choices," he said.
"You could have chosen to protest the Syrian regime's daily savagery against its own people, which has claimed thousands of lives.
"You could have chosen to protest the Iranian regime's brutal crackdown on dissent and support of terrorism throughout the world," he said.
"You could have chosen to protest Hamas rule in Gaza, where terror organisations commit a double war crime by firing rockets at civilians and hiding behind civilians."
Netanyahu said Israel was "the Middle East's sole democracy, where women are equal... human rights organisations can operate freely, religious freedom is protected for all.
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"We therefore suggest that you first solve the real problems of the region, and then come back and share with us your experience," he said.
The Guardian newspaper reported that Jet2.com had contacted three female passengers late Friday to inform them that their seats had been cancelled. They had booked a flight to Tel Aviv scheduled to leave Manchester, northwest England, at 0900 GMT on Sunday.
A company spokeswoman declined to comment on the number of affected passengers.
"Jet2.com was informed by the Israeli authorities that certain passengers booked to travel on flight LS907 would not be permitted to enter Israel," the company said in a statement.
"We were further advised that if we were to allow them to travel, we would be responsible for their immediate return to the UK."
Lufthansa on Friday cancelled dozens of tickets of pro-Palestinian activists for this weekend, saying it was complying with Israeli advice.
Air France said Saturday it had withdrawn tickets for flights Sunday from Paris's main Charles de Gaulle airport and from Nice on the southwest coast.
"Under the Chicago Convention, Air France refuses to embark any passenger not admissible by Israel," a spokeswoman said.
She declined to say how many passengers named by Israel as undesirable had been affected.
The so-called "Welcome to Palestine" campaign is taking place for a third consecutive year.
The campaign's organisers in the West Bank say they want to publicise Israel's control of movement into and out of the Palestinian territory and to boost solidarity with the Palestinian people.
The campaign has been dubbed a "flytilla", echoing attempts by activists to reach the Palestinian Gaza Strip by boat in so-called Freedom Flotillas in spite of an Israeli blockade.