Authorities said they were now "convinced" their first arrest a man named as Adem Karadag planted the bomb on August 17 which killed 20 people after weeks of an often confusing and contradictory police investigation.

Earlier police said it was unlikely that either of the two foreign men held in custody over the unprecedented and unclaimed attack on the Thai capital were the key suspect as they issued arrest warrants and hunted for several others.

But on Saturday national police spokesman Prawut Thavornsiri said further probing had revealed Karadag whose nationality remains unconfirmed was the bomber.

"It is confirmed that Adem is the man in the yellow shirt based on CCTV footage eyewitness accounts and his own confession" Prawut said.

"After he placed the bomb at the shrine he called a motorbike taxi and changed his shirt at a restroom in (nearby) Lumpini Park" before travelling to the flat on the outskirts of Bangkok where he was arrested last month.

On Saturday afternoon Karadag was taken on a reenactment of his alleged role in the crime -- a standard Thai police procedure -- surrounded by dozens of reporters and passers-by.

Handcuffed and wearing a yellow t-shirt beneath a black bulletproof vest he was escorted around the Erawan shrine nestled between luxury malls and hotels in a bustling downtown district before being driven to Lumpini Park.

Karadag now faces up to eight charges including premeditated murder said Prawut a crime that carries a maximum penalty of death.

Motive unclear -On Saturday national police chief Somyot Poompanmoung told AFP "police were convinced Adem's confession is true" weeks after they said evidence including DNA tests could not confirm Karadag was the bomber.

But the suspect's lawyer told AFP he didn't believe his client -- who he says is called Bilal Mohammed and was not in Thailand at the time of the attack -- had confessed.

Chuchart Kanphai added that he was denied access to Karadag earlier this week by officials at the military barracks in Bangkok where he is being detained because the suspect was "sick".

The blast last month has left Thailand stunned and dealt a fresh blow to its reputation as a tourist haven -- the majority of the fatalities were Chinese visitors who believe prayers at the shrine bring good fortune

The motive is still unclear but security experts have increasingly suggested links with militants from China's Uighur minority -- or their ethnic Turkic supporters -- with the passports ethnicities and travel plans of key suspects appearing to point in that direction.

They have speculated the attack was revenge for Thailand's forced deportation of 109 Uighur asylum-seekers to China in July a move that ignited anger in Turkey where nationalist hardliners see the minority as part of a global Turkic-speaking family.

Karadag's lawyer has previously said his client was born in the western Chinese region of Xinjiang home to around 10 million Uighurs but moved to Turkey in 2004 where he received Turkish nationality.

The other man in custody has been identified as Yusufu Mieraili who was seized with a Chinese passport marking Xinjiang as his birthplace. Police believe the passport is real but have not confirmed his nationality either.

Thai officials have strenuously avoided using the word Uighur largely analysts say for fear of putting off tourists or angering China -- one of the ruling junta's few international friends.

Police chief Somyot linked them to the attack for the first time last week but only in reference to their theory that the blast was conducted by a gang of people-smugglers in revenge for a Thai crackdown on their lucrative trade including the transfer of Uighurs.

The mostly Muslim minority have long accused Beijing of religious and cultural repression in Xinjiang with hundreds believed to have fled in recent years often heading to Turkey via Southeast Asia.