Police also say they lack modern facial recognition technology to decipher who the bomber is from the grainy security camera footage.
“Sometimes there are 20 cameras on the street but only five work”, he said on Monday. “We have to waste time putting the dots together”.
At least 20 people were killed and more than 100 injured in last Monday’s explosion.
Police on Tuesday said the search for those behind the attack, which took place less than 300 meters from the national police headquarters, has narrowed, as they come under increasing public pressure to catch perpetrators.
While a police spokesperson shared on Thai television that he suspects the man may have left the country, the national police chief Somyot Poompanmoung does not agree.
Last week junta chief Prayut Chan-O-Cha publicly bristled at any suggestions Thailand might ask for foreign investigators, though he has said he is open to technical advice from overseas.
A reward of Bht1 million ($28,000) has been offered to anyone who can provide information on the man that police are now referring to as “the bomber”.
Almost a week after the Bangkok bombing, authorities appear no closer to identifying suspects or a motive, while officials have issued contradictory statements about the suspect’s appearance, the number of accomplices he might have had and the chances of foreign involvement, according to reports.
A journalist organisation in Thailand has said it it “dismayed” after a Hong Kong-based photo reporter was arrested and charged for carrying body armour and a helmet after covering the deadly bomb attack at a Bangkok shrine.
“Since the bombing, we’ve barely slept”.
“We have given training to restaurant and bar staff, motorcycle taxi drivers, as well as tour guides to help spot the bomb suspect and suspicious items”, said Pol Lt Col Udomraksusup.
The Tourism Monitoring and Communication Centre of the Tourism Authority of Thailand (TAT), with 27 overseas offices and 35 domestic offices, is closely monitoring as well as assessing the situation, and will be providing regular updates.
The grainy security video shows the main suspect wearing a yellow T-shirt and shorts and sitting down on the bench where he then leaves his backpack.
Grilled about what progress has been made in a week, the police chief said that basic questions about the suspect’s identity and whereabouts remain unknown.