The number of Israeli pirate radio stations has exploded in recent years. They are often the mouthpieces of ultra-Othodox Jewish groups and political extremists.

The authorities at Ben Gurion airport say the pirate broadcasters using the same wavelengths as aircraft have almost caused a number of air disasters.

The airport was closed for one hour on Tuesday in protest at the interference, delaying the departures of 11 airliners.

Danger

"This situation is very dangerous because we can no longer ensure air traffic security," said Avia Hacohen, head of the air traffic controllers association.

There are between 100 to 150 pirate radio stations in Israel, an enormous number in this small country.

Head of police investigations, Yossi Sedbon, says police have closed more than 100 pirate broadcasters over the past 18 months.

The problem is that offenders can return to the airwaves quickly because they are well-organised and usually have back up equipment.

"The delinquents that we arrest receive only symbolic fines or at most suspended prison sentences when the law allows for up to three years in prison for this offence," Commissioner Sedborn said on Tuesday.

Some pirate broadcasters have been convicted several times for the same offence, he added.

War on pirates

Pirate radio has played a controversial role in recent Israeli history.

Critics blame certain illegal radio stations for helping create the atmosphere of incitement which led a Jewish extremist to assassinate Prime Minister Yitzhak Rabin in 1995.

During the recent elections, outgoing Prime Minister Binyamin Netanyahu gave an electioneering interview on one ultra-nationalist station while the polls were open.

Both he and the station were roundly criticised for what was a most unusual breach of election convention.

The Israeli ministers of police, communications and transport are expected to meet on Wednesday to to discuss the issue of pirate radios.