Thailand's crippling political crisis shifted its focus on Thursday from Bangkok's gradually opening Suvarnabhumi airport to King Bhumibol Adulyadej, who will address the nation on the eve of his 81st birthday.

The revered monarch, thrust into the centre of the political fray by the anti-government People's Alliance for Democracy's (PAD) persistent invocation of his name, is due to make his remarks on radio after 0900 GMT.

Bringing hope to 230,000 stranded foreign tourists, Airports of Thailand said the $4 billion Suvarnabhumi airport, one of Asia's largest, would resume 'full service' at 0400 GMT on Friday after a week-long shutdown by PAD protesters.

Thai Airways said it had 12 flights out of the 125,000 passenger-a-day hub on Thursday, but sources said other carriers were being rail-roaded into getting back in the air and were worried about short-cuts to safety and security procedures.

'We are under enormous pressure to open -- from the airport authorities, from stuck passengers, from shareholders, from the tourist industry,' said one airline official who asked not to be named. 'But our genuine security concerns are being ignored.'    

The airport shutdown has already cost the tourism- and export-dependent economy hundreds of millions of dollars.

The central bank slashed interest rates by a shock 100 basis points to 2.75 percent on Wednesday, reflecting the impact of the airport siege -- the latest twist in a 3-year political crisis -- on an economy already feeling the effects of a global slowdown.

Whether the king can calm the waters remains to be seen.

Regarded as semi-divine by many Thais, he has intervened decisively in politics three times during his six decades on the throne, favouring both democratic and military administrations.

His remarks in the last three years have been nuanced and focused on the need for national unity, although his calls for clean government were widely read as a swipe at Thaksin Shinawatra, the populist prime minister ousted in a 2006 coup.

Despite the return of relative normality, analysts said more trouble was in store after the hiatus of the king's birthday when parliament meets on Monday to select a replacement for Prime Minister Somchai Wongsawat, sacked by the courts this week.

Somchai's People Power Party (PPP), which the PAD accuses of being a front for the now exiled Thaksin, was dissolved in the same ruling but most of its rank-and-file members simply switched to another 'shell' party.

It and the other five parties in the ruling coalition have more than enough numbers in parliament to form the next administration, an eventuality that is bound to cause the PAD to resume its street protests.

'I am sad that we are going,' said Ranatip, 48, an unemployed office assistant told Reuters as she packed up her belongings at the PAD airport sit-in. 'But I am ready to fight for my king and my country. I will come back as soon as I am needed.'    

With so many of the country's key institutions compromised, analysts say the fundamental stand-off will persist between Bangkok's royalist and military elite, and the forces of the rural and urban poor broadly aligned with Thaksin.

'Thailand remains locked in this structurally flawed system for the foreseeable future,' said IHS Global Insight analyst Kristina Azmi. 'The risk of civil unrest is growing and with it the accompanying risk of military intervention.' -Reuters