Security is being tightened at Thai transport hubs, after a series of bomb attacks in the troubled south.
On Sunday three bombs killed two people and injured at least 60. On Monday another bomb exploded in Yala province, injuring four soldiers.
In the last year more than 600 people have died in Thailand's Muslim south, in attacks blamed on Islamic militants.
Thai Prime Minister Thaksin Shinawatra condemned the violence, but said he would not use force to retaliate.
Last week he signalled he was considering a softer line on the southern issue.
Monday's bomb was detonated while senior government officials held an emergency meeting to discuss the three bombs overnight, according to the BBC correspondent in Thailand, Kylie Morris.
Two of Sunday's blasts happened in the city of Hat Yai, where the airport and a supermarket were targeted.
Another bomb went off outside a hotel in the town of Songkhla, some 40km (25 miles) to the north.
Eyewitnesses described the scene in the domestic arrivals lounge of Hat Yai airport, where both of the fatalities occurred. Hospital officials say a number of those injured have lost legs and arms in the explosion. Among those wounded were a French and an American tourist.
The city is the main transport hub for the far south, with most flights bound for other destinations inside Thailand.
Twenty kilometres (12 miles) away, another bomb was planted in a rubbish bin outside the Carrefour superstore, part of the French-owned chain.
Many people were at the store for Sunday evening shopping and at least five were wounded there. The force of the blast shattered the store's front windows.
At least 60 people were injured in the two blasts.
The third explosion, outside a hotel in Songkhla City, is thought to have been caused by a bomb placed on a motorbike. There were no casualties there.
The BBC's correspondent in Bangkok, Kylie Morris, says that over the past year Thailand has become accustomed to attacks in the deep south - shootings and small bombings normally targeted at police or soldiers.
But the bombs in Hat Yai represent the first major attacks outside the three southernmost provinces, our correspondent says.
At Monday's security meeting, officials were told that closed-circuit video at the airport had captured on film a man suspected of planting the bomb there.
The interior minister has said in order to restore people's confidence, security officials will bring into force the kind of stringent measures which were in place at the Apec summit hosted by Bangkok two years ago.
The Thai government has been criticised by human rights groups and Muslim countries over what they call heavy-handed tactics in the south.
But last week, Mr Thaksin indicated he was reconsidering his approach to dealing with the unrest - pledging to pull out some troops in the south, and to focus on providing the area with more development and education.
BBC full story
Southern bombings are getting closer
Just a quick note on this article regarding the bomb at Hat Yai airport.
This is definitely not the first attack in the city. The train station has been targetted in the past. Indeed, the troubles in HY and down south have been around for years.
I wouldn't be too alarmed at present up here in HH. Attacks have always been carried out from HY south so far. The Islamic groups have warned that they may go for Bangkok though.
This is definitely not the first attack in the city. The train station has been targetted in the past. Indeed, the troubles in HY and down south have been around for years.
I wouldn't be too alarmed at present up here in HH. Attacks have always been carried out from HY south so far. The Islamic groups have warned that they may go for Bangkok though.