Thais and tourists headed warily into the main part of a big holiday weekend yesterday as police looked for suspects and a motive behind a series of blasts that shook resort towns across Thailand, killing four people and wounding dozens more.

There was no claim of responsibility for the attacks on Thursday and Friday, which followed a successful referendum last weekend on a new constitution critics say will bolster the military's power for years to come.

The political party whose governments have been overthrown by the country's ruling generals, last night denied having any role in the attacks. Analysts say suspicion would inevitably on fall on enemies of the ruling junta beaten in the referendum or insurgents from Muslim-majority provinces in the south of the mostly Buddhist country.

Fears that followers of former prime ministers Thaksin Shinawatra and his sister Yingluck Shinawatra, including an opposition movement sympathetic to the Shinawatras known as the "red shirts", could be blamed prompted a senior figure in their Puea Thai Party to issue a sharp denial.


"People, through social media, are sending messages saying Thaksin Shinawatra is behind these events," Noppadon Pattama, a former foreign minister, said.

"This is slander and defamation. Anyone who is a former prime minister is worried about the country and would not do such evil," said Noppadon, who served in both Thaksin and Yingluk's cabinets.

The violence appeared aimed at dealing a blow to the country's tourism industry, which brings in crucial income to the government.

One small bomb exploded on a beach in Patong on the island of Phuket and four others rattled the seaside resort city of Hua Hin, prompting businesses to shut their doors, streets to empty and anxious tourists to huddle inside their hotels.

Eleven foreigners were wounded, including nationals of Austria, Germany, Italy and the Netherlands.

Police General Pongsapat Pongcharoen, a deputy national police chief, said police were gathering evidence and that international militant groups were not believed to be behind the attacks.

Police said firebombs also triggered blazes at markets and shops in six places, including Phuket, Trang, Surat Thani, Phang Nga and a souvenir shop in the tourist town of Ao Nang, Krabi, a seaside province known for its stunning cliffs.

Prime Minister Prayuth Chan-ocha said the attacks "struck at the hearts of all Thai people".

Royal Thai Police Colonel Krisana Patanacharoen said the bombings followed "a similar pattern used in the southern parts of the country" - a reference to a low-level insurgency in the country's Islamic south that has ground on for more than a decade and killed more than 5000 people.

Southern militants fighting for greater autonomy have carried out sophisticated, coordinated attacks before, but most have hit three provinces in the far south that were not among those targeted this week.

Many tourists interviewed yesterday were resuming their holidays while keeping an eye for any sign of trouble.

"We feel pretty safe. At first we had a lot of mixed feelings, because we didn't know the area well enough," said Lexus Chlorad, 21, from New York, after arriving on Friday.

Carl Suensson, 68, from Sweden, said "today it's pretty OK, but yesterday was scary."

"We follow the news 24 hours. Wherever there's a lot of people, like the market, bars behind Hilton, the train station, we try to avoid it."

The first bomb in the southern province of Trang killed one person and injured six, according to police. Later attackers in Hua Hin hid bombs on a busy street filled with bars and restaurants.

One Thai woman was killed and about 20 people were wounded, 11 of them foreigners.