Frances Harrison BBC correspondent in Colombo

The shift from crackly shortwave was made possible after a controversial decision by the government to allow the rebels to import the necessary equipment.

I don't think you should deprive the parties to the negotiations of the opportunity of expressing their point of view GL Peiris government spokesman

The idea is the programmes will help support the current peace process aimed at resolving 20 years of civil war.

But critics of the move say the government has handed the rebels a powerful propaganda tool.

For years, Voice of Tigers, as the rebel station is known, was illegal.

But the government recently allowed the Tigers to import more than $100,000 worth of sophisticated broadcast equipment, including two FM transmitters and enough machines to outfit a modern radio station.

Freedom of speech

Questions were asked about the security implications of the move, with critics arguing it is too early in the peace process to issue the rebels a licence to broadcast legally.

The rebels appear to be preparing for peace

But government spokesman GL Peiris says it is healthy to allow all sides in the peace process to put their views across.

"Now the parties are talking to each other and they're trying to arrive at a political resolution of the conflict," he told the BBC.

"Under those circumstances it is not sensible to gag one party. I think both parties must have the capability to express their views.

"Let the public decide whether their views are right or wrong, convincing or not convincing."

Changed times

The Tigers have expanded their output to eight-and-a-half hours a day of programming in two different languages.

They say their aim is to inform people in the conflict areas about the peace process.

But it is likely to be a one-sided view of events.

Voice of Tigers has been the official propaganda organ of the movement.

Over the years it has specialised in broadcasting battle reviews, biographies of famous suicide fighters, as well as educational programmes and local news.

But it is a remarkable sign of how much things have changed in Sri Lanka that the clandestine radio station the Air Force repeatedly claimed it had knocked out in bombing raids is now a legitimate broadcaster on FM.