A Thai court on Monday issued two more arrest warrants to accompany police sketches of a man and woman suspected of involvement in a central Bangkok bombing in which 20 people died.

The warrants for a Thai Muslim woman and what appears to be a foreigner come in the wake of weekend raids on an apartment complex in a Bangkok suburb, which yielded the arrest of a chief suspect and equipment that may have been used in the construction of an explosive device.

"We would like to ask owners of apartments, dorms or rental houses that have residents whose appearances match these descriptions to immediately contact security officers, because these individuals may have materials that could be dangerous to the buildings or other residents," police spokesperson General Prawut Thavornsiri said in a televised statement.

The woman - shown in the new sketches and on her ID card wearing a hijab - is a 26-year-old Thai who rented out an apartment where two bags of fertilizer, gunpowder, a bag of bolts and a remote controlled car - all of which can be used in the construction of a bomb - were found.

On Monday, Khaosod website reported that officials had searched her family home in southern Phang Nga province.

It said that no illegal items were found in the search, while her family said that she had not been home for three months.

The second sketch is of a young man of apparent Asian or middle-eastern appearance.

Police have not yet revealed if the bomb-making material found in Minburi is similar to that used in the Aug. 17 bombing at a central Bangkok Hindu shrine popular with tourists - in particular Chinese.

They have however said that ball bearings found in the man`s apartment were similar to those used to make the bomb, but underlined that it is still unclear if he is the bomber or an accomplice.

"We have to wait for the forensic police to investigate the evidence in detail to determine whether this evidence is related to the bomb incident at Ratchaprasong intersection," Khaosod reported Bangkok police officer Colonel Susak Parakmakul as saying Sunday.

Thavornsiri has said that the main suspect has since been charged with illegal possession of explosives and is being interrogated at a Bangkok military facility.

Despite initially saying that the young man was refusing to answer questions, Thavornsiri revealed to Thairath that the "interrogation is very useful for the case" and on completion the man "will be sent to police for legal prosecution."

Speculation of a motive has so far focused on elements involved in an insurgency in the country`s south extending a bombing campaign to the capital, internal reaction against the country`s military rulers, people smuggling, and a backlash against Thailand for its deportation of around 100 Uighur to China - to which media have connected Turkish ultranationalists.

The Turkish embassy denied Sunday that the 28-year-old man in custody - who owned a fake Turkish passport with his image - was a Turkish citizen.

Around 200 other counterfeit Turkish passports were also found in his possession.

On Friday, the Thai ambassador in Ankara, Tharit Charungvat, also stressed to Anadolu Agency that Bangkok did not believe there was any involvement from Turkey in the bombing, blaming media misunderstandings.

"Matters can easily be exaggerated and misconstrued by media and press," he said.

General Thavornsiri has since affirmed that the bombing was not related to "international terrorism," but rather to "people smuggling".

"The gang [to which the suspect belongs] is unsatisfied with police arresting illegal entrants," he told a Thai TV channel.

"The suspect had more than 200 fake passports when he was arrested. It is a network that fakes passports and sends the illegal migrants towards third countries."

Residents in the apartment complex where the chief suspect was staying were "ed by the Bangkok Post as saying Monday that he was often visited by another foreigner and that both men "kept to themselves" most of the time.

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