Hundreds of Israeli police, many undercover, gathered at Ben Gurion airport on Sunday to block the arrival of the activists taking part in a "Welcome to Palestine" fly-in, AFP quoted the Israeli police as saying.

Hundreds of Israeli police, many undercover, gathered at Ben Gurion airport on Sunday to block the arrival of activists taking part in a "Welcome to Palestine" fly-in, AFP quoted the Israeli police as saying.

“We have stationed several hundred police in order to maintain order at the airport," Zionist police spokesman Micky Rosenfeld told the news agency.

Moreover, the Israeli public radio reported that at least 650 uncover police were deployed in and around the airport with orders “to exercise restraint, but to intercept any troublemakers.”

In parallel, at least 120 passengers demonstrated at Brussels airport after a number of them were barred from flying to Tel Aviv, with police arresting three for disturbing the peace.

AFP quoted activists as saying that at least 60 Belgian and 40 French citizens were unable to fly despite having tickets. Most of them had been due to fly with Brussels Airlines, while the rest were supposed to travel with Lufthansa and Swiss Air.

Dozens of people also protested at Geneva airport where activists said around 30 people had been prevented from boarding an early morning 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.

In Rome, seven Italian activists were prevented from boarding an Alitalia flight, AFP reported.

French carrier Air France and British low-fares airline Jet2.com also said they had cancelled an unspecified number of passengers' tickets to Tel Aviv.

Organizers of the "flytilla" pro-Palestinian campaign, which is in its third year, had been expecting to welcome up to 1,500 people, more than a third of them from France. However, Israel has been preparing since last week to prevent their entry to the occupied territories.

AFP quoted ealier Sunday organizers of the trip as saying that “a lot of people did manage to board planes and a lot of people have been denied."

"We are expecting 1,500 people from at least 15 countries… but most of them from Europe," campaign organizer Mazin Qumsiyeh said, indicating that they were aware of four carriers which had blocked passengers from travelling.

Also Sunday morning, the Israeli police said four passengers had been detained for questioning after disembarking from an El Al flight from Paris, with Rosenfeld clarifying that they were likely to be deported.