BANGKOK (AFP) - Thailand's army chief on Sunday told AFP that the man arrested in connection with last week's deadly Bangkok bomb blast was not cooperating, as the police announced he was part of a people-smuggling gang.
The unidentified foreigner, who is being held in military custody at an undisclosed location, was seized during a Saturday morning raid on a flat on the eastern outskirts of Bangkok.
Investigators say he was found with bomb-making equipment and multiple passports.
"The interrogation is not making progress because the suspect is not really giving useful information," army chief General Udomdej Sitabutr told AFP.
"We have to conduct further interrogations and make him better understand so he will be more cooperative - while we have to be careful not to violate the suspect's rights," he added.
National police spokesman Prawut Thavornsiri said officers believed the suspect was part of a people-smuggling gang who helped illegal migrants obtain counterfeit documents - and that the bomb attack was retaliation for a recent crackdown by Thai authorities.
"They (the gang) are unsatisfied with police arresting illegal entrants," he told Channel 3 in a telephone interview, without elaborating how investigators knew this.
Bangkok has long had a reputation for crime groups that produce counterfeit documents, while Thailand has been a major regional hub for both people-smuggling and people-trafficking.
Pictures released by police on Saturday showed stacks of Turkish passports which were allegedly found at the suspect's flat. Police said they believe the passports are fake.
The authorities have yet to say what nationality the man is.
Mr Prawut told reporters outside police headquarters that investigators were working "with several embassies" to ascertain his identity as well as using multiple translators.
Asked which languages, he confirmed English, but would not be drawn on the others.
Defence Minister Prawit Wongsuwan also told AFP the suspect is known to speak some English.
Other members of the gang are now being sought while DNA samples are being taken from the suspect, police spokesman Prawut added.
For days Thai police have been searching for a network believed to be behind the Erawan shrine attack and another blast the following day beside a busy commuter river pier that caused no injuries.
The investigation has focused on 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.
But the authorities have not yet said whether they believe the suspect now detained is the same as the man in the video footage.
Gen Udomdej told AFP he believed the arrested man was "absolutely involved with the bombs", adding that he "looked like" the suspect seen in CCTV footage.
"But I will not determine whether he is the bomber or not," he added.
Mystery has surrounded the unprecedented bomb blast, for which no group has claimed responsibility.
The blast that hit the Erawan shrine in a busy Bangkok shopping district on Aug 17 was Thailand's worst single mass-casualty attack, killing 20 people - most of them ethnic Chinese tourists from across Asia.
Police and the junta have been keen to play down any suggestion the attack was launched by international terrorists or specifically targeted Chinese tourists.
Potential perpetrators named by the police and experts have included international militants, members of Thailand's southern Malay-Muslim insurgency, militants on both sides of the country's festering political divide or someone with a personal grudge.
In recent days speculation has grown over involvement by China's ethnic Uighur Muslim minority - or their co-religious sympathisers - following Thailand's forced repatriation of more than 100 Uighur refugees last month to an uncertain fate in China.
The sudden repatriation of the Turkic-speaking group, among dozens detained in the kingdom for illegal entry last year after presenting themselves to police as Turkish, triggered fury in Istanbul, with Bangkok's consulate there stormed by protesters.
That speculation was further inflamed by the discovery of the apparent Turkish passports at the suspect's flat.
But Mr Prawit hit out at that speculation and called on both the media and Thais to be patient.
"Don't talk about Turkish or not Turkish," he told AFP. "We have to investigate."