Israel on Sunday barred 40 pro-Palestinian activists who had flown in for a "Welcome to Palestine" campaign as hundreds more would-be protesters were stranded at airports across Europe.

As hundreds of police deployed at Israel´s main international airport in a bid to stop activists from entering, Europe´s main airlines faced a wave of passenger fury after cancelling some 300 tickets following heavy Israeli pressure.

By early afternoon, police had detained 40 passengers on suspicion of being part of the fly-in campaign, better known as the "flytilla," with all facing deportation.

Organisers of "Welcome to Palestine," now in its third year, had been expecting to welcome up to 1,500 people as part of a campaign to expose Israel´s control of movement both into and out of the occupied territories.

But Israel vowed to prevent their entry, warning airlines they would be forced to foot the bill for the activists´ immediate return home in a move which saw many carriers toeing the line.

With airlines cancelling at least 300 passengers´ tickets, scores of activists staged angry demonstrations at airports in several European capitals.

At Brussels airport, protests erupted after at least 100 French and Belgian nationals were unable to board flights with Brussels Airlines, Lufthansa and Swiss Air.

In Geneva, several dozen activists held an angry demonstration after around 45 people out of a group of 70 who had been planning to join the campaign were barred from boarding an easyJet flight.

Scores of activists also protested at Charles de Gaulle in Paris, where airport sources said 90 passengers had been prevented from boarding boarding Lufthansa and Swiss Air flights for Tel Aviv.

Flanked by dozens of anti-riot police, they marched up to the Lufthansa counter to demand an "official written statement" as to why they had not been allowed to fly.

At Istanbul airport, another 50 activists were stranded after Turkish Airlines reportedly refused to allow them on board, Anatolia news agency reported.

In Vienna, Austrian Airlines said five passengers were barred from flights to Tel Aviv, and in Rome, Alitalia turned back seven Italian activists, press reports said.

Air France and two British budget carriers, Jet2.com and easyJet, also barred an unspecified number of passengers, with easyJet confirming it had prevented activists from boarding Israel-bound planes from both London and Switzerland.

Despite the success of its diplomatic campaign to pressure European carriers not to allow activists to board flights for Tel Aviv, Israel deployed hundreds of police at its main international airport with orders to "exercise restraint, but to intercept any troublemakers."

All of Sunday´s arrests took place far from the whirring cameras with police detaining 33 French nationals, two Spaniards, two Italians, one Swiss national, one Canadian and one from Portugal as soon as they landed.

Of that number 27 French nationals were refusing to board planes back to France, immigration spokeswoman Sabine Haddad told AFP, saying they would be "transferred to a detention facility."

The rest had either already been deported or would be sent back later in the day, she said.

Police also arrested another six Israelis and a French national, who were already in the country, for disturbing the peace at various locations in and around the airport.

Not a single protester was identified passing through the main arrivals hall at Terminal 3, an AFP correspondent said, although two protesters from outside the airport who held up signs reading "Free Palestine" were quickly hustled away by police.

Another two men and a woman carrying a handwritten sign reading "Palestine forever" were also quickly removed.

Last year, around 800 people tried to join the campaign, with many blocked from flying by airlines. Another 120 were denied entry by Israel and deported.

Israeli officials hailed their counter campaign as successful. "We have prevented harm to Israel´s sovereignty and also to Israel´s image. The main aim is to prevent violent images and provocations," deputy foreign minister Danny Ayalon told army radio.

Prime Minister Benjamin Netanyahu on Saturday advised activists to concentrate on solving "real problems" in the region.

"We appreciate your choosing to make Israel the object of your humanitarian concerns," he said. "We know there were many other worthy choices. You could have chosen to protest the Syrian regime´s daily savagery against its own people, which has claimed thousands of lives.

"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.

"Have a nice flight." (Copyright © 2012 Agence France Presse. 04/15/12)