Israel deployed hundreds of police Sunday at its main airport to detain activists flying in to protest the country's occupation of Palestinian areas, defying vigorous Israeli government efforts to block their arrival.

Police spokesman Micky Rosenfeld said hundreds of protesters were expected to land at Ben-Gurion International Airport in the course of the day. The police contingent at the airport was reinforced to deal with possible unrest or disruptions, he said.

By late morning, two protesters — one from Canada and another from Portugal — were denied entry and would be placed on return flights, Interior Ministry spokeswoman Sabine Haddad said.

Israel is jittery about the prospect of large numbers of protesters arriving because of deadly confrontations with pro-Palestinian activists in the past, notably a naval raid on a Gaza-bound flotilla in May 2010.

The fly-in's effect has been diluted by airlines that canceled the reservations of at least 100 known activists under pressure from Israel.

Haddad said Israel had sent a list of suspected activists to international airlines, asking the carriers to block them from boarding Israel-bound flights. 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.

Campaign organizer Amira Musallam said she still expected hundreds of pro-Palestinian protesters from around the world to come. Activists who had been barred from flying to Tel Aviv from Charles de Gaulle airport in Paris staged an impromptu protest, she said.

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.

The protest is meant to draw attention to how Israel controls access into Palestinian areas.

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.

Israel limits access to the border crossing to the Hamas-controlled Gaza Strip to foreign journalists, diplomats and aid workers.