The state planning agency reported economic growth of 3.8 percent from the previous quarter, double market expectations of 1.8 percent, but analysts said output over the rest of the year would be hostage to the likelihood of more violence.
Thai stocks, which resumed trading after the exchange closed amid street battles on Wednesday, plunged nearly 3.0 percent on the day, with retail and hotel shares badly affected.
"Investors may be temporarily relieved that a semblance of normalcy has returned, but the political risk remains high and investors will likely be cautious," said Warut Siwasariyanon, head of research at Finansia Syrus Securities in Bangkok.
"The big, underlying conflict is still there and the wound is deeper than ever, even as the roads have been wiped clean." The authorities extended a curfew in the capital and 23 provinces for another seven days on Monday due to fears of continued unrest. The night-time restrictions would be in place from midnight to 4 a.m.
"We have information that there are groups and individuals who still want to create chaos in some areas," army spokesman Sansern Kaewkamnerd told a news conference.
At least 54 people were killed in Bangkok and more than 400 wounded in the latest bout of violence that began on May 14. Almost 40 buildings were set on fire last week as the army dispersed thousands of anti-government protesters who had taken over the commercial heart of the city for weeks.
But the crisis has not been resolved and "red shirt" protesters' plan to resume their campaign for new elections next month.
The planning agency said the 2010 growth forecast was being maintained at 3.5-4.5 percent.
But the forecast would have been 1.5 percent higher if not for the two-month protest in central Bangkok that paralyzed business, decimated the vital tourism industry and depressed consumer spending, the agency said.
Thailand's $264 billion economy grew 12 percent in the first quarter of 2010 from a year earlier, its best rate in 15 years, beating the consensus of 8.9 percent due to a surge in exports and a low base last year.
"Outstanding first-quarter growth was much anticipated but I think what we have to keep an eye on is the second-quarter growth, which will seriously take a hit from political violence in Bangkok," said Pimonwan Mahujchariyawong, an economist at Kasikorn Research Center in Bangkok.
Economists said the disruption to the economy could also persuade the central bank to leave interest rates on hold at a record low 1.25 percent at its next review on June 2.
But, with the protests over, most expect rates to start rising, perhaps from July or August.
Thai bond yields jumped to a three-week high as the market began to price in a rate rise, traders said, but later fell back. Benchmark five-year bond yields rose as much as 13 basis points to 3.32 percent but then trimmed to just 3 bps.
Thailand's five-year credit default swaps, the cost of insuring against a sovereign default, narrowed 10 basis points to 150/160, from a one-year high of 165/175 reached last week as violence escalated between troops and protesters.
The baht firmed slightly, but Thai stocks closed 2.77 percent down, with hotel, retail and transport shares the worst hit.
Central Pattana, which operates Central World, Southeast Asia's second largest department store that was burned down in the riots, dropped 8.8 percent although the company said it expected no significant impact since it was covered by insurance.
Thai Airways fell 6.85 percent on concerns that tourist arrivals would fall, while Bangkok metropolitan train operator BTS lost 7.25 percent on lost revenue during the unrest.
The government said it had received complaints of damage totalling 4.8 billion baht ($148 million) from at least 2,900 individual businesses in central Bangkok.
"This is just an initial estimate based on complaints," said Sathit Wongnongtoey, a minister in the prime minister's office.
"But in the long-term, we may have to consider low-interest loans to small businesses which are affected." On Monday, however, the city of 15 million appeared to be operating as usual, at least on the surface.
Both metropolitan train systems, the Skytrain and the underground, were running after starting a skeletal service over the weekend following disruptions during the protests.
Trains were crowded, but with enough space to stand comfortably, even in rush hour. Government offices and some schools reopened.
"You look around and it feels like nothing has happened," said Dao Pipirom, a 35-year-old market researcher whose apartment is in the business district. "Life goes on as normal now.
"But I still get very agitated when I hear loud noise. I keep thinking it's another grenade blast or gunshot."
