BANGKOK (AFP) - Prime Minister Thaksin Shinawatra today ordered an investigation into a bomb scare campaign that has hit the beleaguered national carrier Thai Airways just months away from a planned share listing.

Thaksin summoned the airline's board members for an emergency meeting on the hoax bomb warnings, believed to be the work of an insider, which delayed flights to Europe on Monday and Wednesday nights.

"It's very bad, some of the Thai Airways staff obviously do not love Thai Airways anymore," told reporters, clearly furious over the latest in a series of damaging incidents at the airline.

"We have to stop the damage being wrought on the airline as soon as possible. I must take decisive action," he snapped.

The first and most serious incident to affect public and investor confidence in Thai Airways came in March when a jet exploded on the tarmac at Bangkok just minutes before Thaksin and his son were due to board.

Investigators ruled out sabotage, and suggested that overheating air conditioning units may have been to blame.

Service 'sucked'

Since the near-disaster, the airline has faced industrial action between pilots and unions, disappointing balance sheets and a series of tongue-lashings from the premier who famously said its service "sucked".

Thaksin ordered the airline to come up with a long-term plan to overhaul its operations, improve standards, and work out how to complete in an intensely competitive global environment.

And on Wednesday he stepped up the rhetoric, vowing to purge the entire airline and saying its managers were were running out of time to come up with a strategic plan.

"There will be a lot of changes, but I can't say right now what will be changed, I can only reassure you that major charges will take place," he said.

The prime minister said he was confident that those responsible for this week's bomb scares would be identified, after he assigned a number of government agencies to examine the evidence.

In the first incident, a leaflet was left in a secure crew room at Bangkok's international airport, warning that flight TG942 to Rome and Madrid had a bomb on board.

On Wednesday night, the Thai Airways office in Rome received a fax saying that a device was on the flight which leaves Bangkok at midnight seven days a week.

Critical time

The Boeing 747-400 was pulled out of its parking bay and thoroughly searched before being allowed to take off with a one-and-a-half-hour delay, Thai Airways officials said.

The scare campaign comes at a critical time for the airline as it struggles to streamline its debt-ridden operations in preparation for a major listing later this year which will divest at least 13 percent of the company.

Analysts said that even without the new problems cropping up this week, Thai Airways had a lot of work to do ahead of the share float, particularly in regard to a plan to sell a 10 percent stake to a strategic partner.

"Thai Airways has got so many challenges ahead of it," said Andrew Maule from ABN Amro Securities.

"The government was meant to accelerate the share sale and the first thing it did when it came to power was to say it wasn't going to sell to a strategic partner. It's been going back and forth. I wouldn't hold my breath on them."

The share sale is part of Thailand's commitments to the International Monetary Fund under a 17.2 billion dollar rescue package approved in 1997 at the height of the regional economic crisis.