Thai security officials, unsure whether the suspected bomber responsible for last week's bomb blast near the Erawan Shrine in central Bangkok is still in the country, are seeking more witnesses and evidence.

The police need more witnesses and evidence, especially closed-circuit television camera footages for further investigation into the two bomb explosions in Bangkok last week, said Police General Jakthip Chaijinda.

The Royal Thai Police deputy chief said the results of the DNA tests taken at the Erawan Shrine incident, banknotes used by the suspected bomber and the tuk-tuk he was ferried in, were expected to come out tomorrow.

However, the sketch of the bombing suspect at Sathorn pier had still not been finalised, he said in a briefing to the press after chairing the investigation team meeting.

The bomb blast near the Erawan Shrine killed 20 people and injured 130 more, while none was killed or injured in the blast at the Sathorn pier located at the Chao Phraya river which was used to get to many tourist attractions in Bangkok.

Jakthip said the bomb experts initially concluded that TNT explosives were used in the two bombs.