The Criminal Court yesterday issued an arrest warrant for a man police said was involved in the bomb attack near Bangkok's Saphan Khwai intersection on New Year's Eve.

Head investigator and deputy National Police chief Jongrak Juthanont said the suspect, whose identity is still unknown, was charged with five offences including terrorism, attempted murder of police on duty and possession of explosives without authorisation.

Jongrak will on Monday seek permission from acting National Police chief Seripisut Temiyavej to make public a video grab of the suspect captured by a surveillance camera at the intersection in Bang Sue district.

The hope is that the combination of issuing an arrest warrant and releasing the video will lead to a member of the public identifying the bombing suspect.

Jongrak said police had not yet obtained any leads indicating a link between the Saphan Khwai man and Ramkhamhaeng University dropout Thawalsak Paenae, who was seen in footage taken at the Seacon Square shopping mall - another of the nine bomb sites.

Justice Ministry permanent secretary Charan Pakdithanakul played down media coverage reporting conflicts between police and his ministry's Department of Special Investigation (DSI) over the Bangkok bombings investigation, saying any confusion was due to "unsynchronised communication" between both agencies.

He said the DSI had become involved in the probe only at the order of the prime minister and police were the key players in working everything out.

However, a study was under way to authorise the DSI to initiate investigations into national security cases on its own, he added.

DSI director-general Sunai Manomai-udom said his department was willing to function as a support unit after it handed investigating authority to police.

The DSI's focus was on solving the Seacon Square bomb case and the suspects carrying out the attack. He expressed confidence the perpetrators would be brought to justice.