THAILAND'S revered King Bhumibol Adulyadej celebrates his 81st birthday this Friday.

His 65 million subjects are awaiting his usual birthday-eve speech with special keenness - and will be noting every nuance.

With Bangkok's airports in the grip of anti-government protesters and with pro-government demonstrators now massing, many think only the right whisper from the monarch, now reigning for 61 years, can resolve the crisis peacefully.

Others are not sure: "No doubt His Majesty is very concerned with the well-being of the people and has always been there to help them. But I think it's too burdensome to pass the buck to the King," Dr Kriengsak Chareonwongsak, a former MP and prominent economist, told Bernama.

Still, the King has intervened to end hostilities before - most notably in 1992, when he summoned coup leader Suchinda Kraprayoonand and pro-democracy leader Chamlong Srimuang to a televised audience.

Mr Chamlong is now a key leader of the royalist People's Alliance for Democracy (PAD), the group leading the protests.

Yesterday, the PAD ended its three-month seizure of the Prime Minister's offices, but redeployed to tighten its grip on the airports. The protesters' numbers swelled to 6,000.

The PAD said it abandoned Government House because of recent grenade attacks, which killed two and wounded dozens.

However, their demands have not budged: That the government of Premier Somchai Wongsawat resign. The PAD calls it a proxy for convicted former premier Thaksin Shinawatra.

At least the PAD departure from Government House eased the danger of clashes with the pro-government group now camped out for a second day just a few kilometres away.

Just as the PAD are known as the "Yellow Shirts" due to the colour of their attire, which symbolises devotion to the King, the government's supporters are dubbed the "Red Shirts".

Fresh tensions are now brewing after the Red Shirts threatened a blockade of Thailand's Constitutional Court, which is due today to wrap up a vote fraud case that could disband the ruling party and bar Mr Somchai from politics.

The police have asked the army to help guard the court. No date for a verdict has been given.

Meanwhile, the PAD blockade claimed its first foreign victim yesterday, a Hong Kong man who died in a traffic accident while travelling to southern Phuket town, where he hoped to catch a flight home.