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 on Saturday they had joined Germany's Lufthansa in cancelling seats on flights to Tel Aviv.
At Geneva airport a hundred pro-Palestinian activists were being prevented by Swiss police early on Sunday from boarding a flight bound for Tel Aviv, the "Welcome to Palestine" campaign said.
There was a high police presence at the airport and one of the activists had their passport confiscated, campaign spokesman Anas Muhammed told AFP by phone.
At Paris' main Charles de Gaulle airport, several dozen activists demonstrated after being prevented from boarding Lufthansa and Swiss Air flights for Tel Aviv early Sunday.
Flanked by dozens of anti-riot police, they went to the Lufthansa counter to demand an "official written statement" as to why they had not been allowed to fly.
"Our movement is totally peaceful but unfortunately we are still being treated like trouble-makers," one of the campaign's organisers in France, Olivier Buchotte, told AFP.
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.
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 09h00 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 on Saturday it had withdrawn tickets for flights Sunday from Paris's Charles de Gaulle airport and from Nice on the southwest coast.
"Under the Chicago Convention, Air France refuses to embark any passenger not admissable by Israel," a spokeswoman said, while declining to say how many passengers were 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.