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 scores of 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 now likely to be deported.

They were 33 French nationals, two from Spain, two Italians, one Swiss, one Canadian and one from Portugal.

"Another six Israelis and a French national were detained for disturbing the peace at the airport," police spokeswoman Luba Samri said, indicating they were already in the country and had not arrived by plane.

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.

Scores of angry activists staged angry demonstrations at airports in several European capitals after being prevented from boarding flights despite having bought tickets.

At Brussels airport, protests erupted after at least 100 French and Belgian nationals were unable to fly.

Most had been due to fly with Brussels Airlines, while the rest were supposed to travel with 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.

A similar number protested at Charles de Gaulle airport in Paris after being stopped from 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 Britain's budget carrier, Jet2.com, also barred an unspecified number of passengers, officials said.

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."

The latest arrests were made on an easyJet flight from Geneva, with organisers saying around 30 French nationals were arrested after landing at midday.

But at Terminal 3, the main venue for international arrivals, things were mainly quiet. Two protesters from outside the airport with signs reading "Free Palestine" were quickly hustled away by police, an AFP correspondent said.

An ultra-nationalist Israeli MP and several other extremists were on hand to welcome any activists who slipped through the tight security cordon, waving Israeli flags and signs reading: "Go to Syria," he said.

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."