JERUSALEM – Israel detained dozens of international activists as they landed at its main airport on Sunday, preventing them from entering the country to participate in a planned solidarity mission with Palestinians in the West Bank.

Israel said the activists, part of an umbrella group called "Welcome to Palestine," were provocateurs who posed a security threat. But organizers said the event, meant to draw attention to Israeli travel restrictions on Palestinians, was nonviolent, and they accused Israel of using heavy-handed tactics to stamp out legitimate protest.

Israel is jittery about the prospect of a large influx of foreign protesters arriving because of deadly confrontations with pro- Palestinian activists in the past. In the worst instance, Israeli naval commandos clashed with activists on board a flotilla trying to break Israel´s blockade of the Gaza Strip in May 2010, killing nine activists.

By early evening, the Interior Ministry said a total of 49 people had been stopped at the airport, most on flights from France, but also from Spain, Switzerland, Canada, Italy and Portugal. At least 12 were placed on flights back home, while arrangements were being made to expel the others.

Hundreds of police were deployed in and around the airport. Police spokesman Micky Rosenfeld said nine Israeli sympathizers were questioned at the airport after causing "public disturbances," such as unfurling pro-Palestinian banners. No other unrest was reported.

Asked why Israeli authorities consider this particular group of activists a threat, Rosenfeld replied that they have "security backgrounds" or were "involved previously in different activities," including "security issues concerning Israel."

He would not elaborate.

Hundreds of additional activists were expected to arrive on flights later Sunday.

Amira Musallam, one of the coordinators for "Welcome to Palestine," said she was aware of only two activists making it through the airport. She said participants had been told not to lie if questioned at the airport, and that the weeklong program was now in doubt. The program included a project to renovate a school, give participants tours, plant trees and "get to know the Palestinian territories."

"The aim of ´Welcome to Palestine´ is when we have guests coming to Palestine — to Ramallah, Hebron, to Bethlehem, they should be able to say we are going to Palestine and not to lie. They (Israel) forbids people to visit, they are controlling all the borders," she said.

Israel took action over the weekend to prevent the fly-in from ever taking place by pressing airlines not to allow at least 100, maybe more, known activists, to board their flights.

Interior Ministry spokeswoman Sabine Haddad said Israel had sent a list of suspected activists who would not be allowed into the country. It warned the airlines they would have to cover the cost of the activists´ return flights, and threatened unspecified sanctions on airlines if they did not comply, she said.

Prime Minister Benjamin Netanyahu praised the Israeli police for foiling the activists´ plans and called the activists misguided.

"If they want to come check human rights, have them go to Syria. Maybe they can stop the massacre of thousands of innocents. Have them go to Iran and stop the stoning of women. Have them go to Gaza and stop the practice of using children as a human shield for terrorists who fire rockets on our citizens," he said.

The protest is meant to draw attention to how Israel controls access into Palestinian areas. The Palestinians claim the West Bank, east Jerusalem, and Gaza Strip, all captured by Israel in the 1967 Mideast war, for their future state.

Visitors can only reach the West Bank through Israeli-controlled land crossings or Israeli airports, though at any given time, hundreds of foreigners, including activists, are in the territory, which Israel captured in 1967.

Travelers headed for Palestinian-controlled areas of the West Bank often report being detained and questioned, sometimes for hours, by Israeli border authorities.

In a related development, Israeli TV channels broadcast footage Sunday of a senior military officer assaulting an unarmed activist who was protesting near the West Bank city of Jericho. In the video, the Lt. Col. is seen striking the activist in the mouth with the butt of his rifle´s magazine.

In response, the military said it viewed the incident seriously, and it was being investigated.

Israel restricts access to the border crossing with the Hamas- controlled Gaza Strip to foreign journalists, diplomats and aid workers. Some 1.6 million Palestinians live there.

Last July, Israel blocked a similar fly-in effort by preventing dozens from boarding Tel Aviv-bound flights in Europe and denying entry to 69.

Some Israelis accused the government of overreacting to the activists´ campaign.

"Instead of waiting to present the crackpot activists with flowers, putting them on buses and leading them directly to their destination in Bethlehem, the heads of the defense establishment and security forces have once again lost their minds," columnist Eitan Haber wrote in the Yediot Ahronot newspaper. (© 2012 The Associated Press 04/15/12)