Thai authorities on Saturday detained and charged a 28-year-old Turkish man over a bomb attack in Bangkok last week that killed 20 people and wounded scores more.
It is the first arrest in connection with the 17 August bombing at the Erawan shrine in the capital's bustling downtown district, which killed mostly Asian visitors, in Thailand's worst single mass-casualty attack.
Around 100 police and military officers -- including at least a dozen bomb disposal specialists -- gathered outside an apartment block in Nong Chok district on the eastern outskirts of Bangkok where the man was arrested Saturday in possession of bomb-making equipment and multiple passports.
"We believe that the suspect was involved with the bombing" at the shrine, national police spokesman Prawut Thavornsiri said on a live televised broadcast Saturday evening.
He also said that the man was involved with a blast the day after the shrine bombing near a popular tourist pier which sent people scurrying but caused no injuries.
The 28-year-old has been charged with the "illegal possession of bomb-making materials such as ball bearings" and "pipes to use as a bomb container", Prawut said.
Colonel Banphot Phunphien, spokesman of Thailand's Internal Security Operations Command (ISOC), told AFP the man was a "Turkish national".
For days Thai police have been searching for a prime suspect, described as a foreign man, who was captured on security footage wearing a yellow t-shirt and leaving a bag at the shrine moments before the blast on security cameras.
But authorities have not yet linked the suspect now detained in military custody with the man seen on this video footage.
"We found dozens of passports inside his room, we have to check which nationalities they belong to," he said on the televised broadcast.
In earlier comments on Thai broadcaster Channel 3, Prawut said the "clothes and bomb-making materials" found in the accused's room were linked to both recent blasts.
"The ball bearing is the same size" as those found at the two blast sites, he said.
- Multiple theories -
The attack on the Hindu shrine in Bangkok last week has left the vibrant city rattled and dealt a fresh blow to the kingdom's reputation as a welcoming and safe travel destination.
The majority of those killed were ethnic Chinese worshippers from across Asia, who flocked to the shrine in the belief that prayers there bring good fortune.
Investigators have said the attack was clearly aimed at damaging the tourism industry but insist that Chinese tourists -- who visit Thailand in larger numbers than any other nationality -- were not singled out.
Earlier this week Thai police said they were not ready to exclude any possibility about who was behind the attack.
But speculation had grown over China's ethnic Uighur Muslim minority -- or their co-religious sympathisers -- being behind the attack, motivated by Thailand's forced repatriation of more than 100 Uighur refugees last month to an uncertain fate in China.
Bangkok's consulate in Istanbul was stormed by angry protesters after the forced repatriation.
On Friday police said three Uighur Muslims, among dozens detained in the kingdom for illegal entry last year, had been questioned in eastern Sa Kaeo province, bordering Cambodia, over the bombing but provided no further details.
Earlier this week regional security analyst Anthony Davis from IHS-Jane's said a potential perpetrator could be people from or affilated to the extreme right-wing Pan-Turkic movement known as the Grey Wolves, who have latched onto the Uighur cause in recent years.
In comments during a discussion on the blast at the Foreign Correspondents' Club of Thailand (FCCT) Davis said the group had close links with Turkish organised crime, who are known to have a presence in Bangkok, and were at the forefront of the attack on the Thai consulate in Istanbul.
His remarks were widely carried in the Thai press but police refused to state whether they believed the perpetrators had a Turkish connection.
Other potential perpetrators named by the police and experts have included international jihadists, members of Thailand's southern Malay-Muslim insurgency, militants on both sides of Thailand's festering political divide or even someone with a personal grudge.