Israeli police on Sunday prepared to deport two activists who had flown in as part of the "Welcome to Palestine" campaign, as hundreds of police fanned out through Ben Gurion airport.
Police said they had stationed "several hundred" officers at Israel's main international airport near Tel Aviv, with public radio reporting more than 650 undercover police in place, with orders to "exercise restraint, but to intercept any troublemakers."
Police spokeswoman Luba Samri told AFP five passengers had been "detained for questioning" with three of them allowed in, and another two facing deportation.
Three French nationals who arrived on an El Al flight from Paris were allowed in, but a Portuguese activist who flew in from Amman with Royal Jordanian Airlines was to be deported, as was a Canadian who arrived on United Airlines, she said.
Organisers of the so-called "flytilla" 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.
But Israel has vowed to prevent their entry, and after warning foreign airlines they would be forced to foot the bill for the activists' immediate return, at least four European carriers cancelled tickets for a number of passengers heading to Tel Aviv.
An AFP correspondent at Terminal 3, the main arrivals area for international flights, said there were only a handful of uniformed officers inside the building, alongside nine border police, none of whom was carrying a weapon.
Since Friday, Air France, Britain's budget carrier Jet2.com, Germany's Lufthansa and Swiss Air have all prevented an unspecified number of passengers from flying to Tel Aviv, European officials said.
But organisers of the "Welcome to Palestine" campaign on Sunday said many more had successfully managed to board flights heading for Israel, where on arrival they were expected to openly declare their intention to visit the West Bank.
"A lot of people did manage to board planes and a lot of people have been denied," campaign organiser Mazin Qumsiyeh said, without giving numbers.
He said they were aware of four carriers which had blocked passengers from travelling -- Lufthansa, Air France, Jet2.com and Brussels Airlines. He did not mention Swiss Air.
"We are expecting 1,500 people from at least 15 countries," Qumsiyeh said, indicating that most of them were expected to fly from Europe.
Israel's hawkish deputy foreign minister Danny Ayalon said the Jewish state's attempts to prevent the campaign had succeeded.
"We have prevented harm to Israel's sovereignty and also to Israel's image. The main aim is to prevent violent images and provocations," he told army radio.
"Most of the work was diplomatic to prevent a situation in which there was any sort of confrontation between demonstrators and Israeli security forces."
Last year, around 800 people tried to join the campaign, with many blocked from flying by the airlines. Another 120 were denied entry by Israel, then sent back to their home countries.
The campaign's organisers say they want to publicise Israel's control of movement into and out of the occupied Palestinian territories and to demonstrate solidarity with the Palestinian people.
The term "flytilla" recalls several attempts by pro-Palestinian activists to reach the Israeli-blockaded Gaza Strip by boat, which have come to be known as "Freedom Flotillas."