"At this time, nine people have been arrested and the investigation will go on," Prime Minister Prayut Chan-ocha said during a press conference. Several small-scale homemade explosives were detonated last Friday across the city.
The blasts left four injured and the police found another three unexploded devices.
The explosions occurred just before US Secretary of State Mike Pompeo was to deliver an address on the sidelines of meetings between Foreign Ministers of the Association of Southeast Asian Nations (ASEAN) and the bloc's external partners, including China and the European Union.
Authorities have not disclosed a motive for the attacks, but Deputy Prime Minister Prawit Wongsuwan said on Tuesday that the attackers were linked to a group from the South, although he did not elaborate except to say that investigations were ongoing, Efe news reported.
Prawit's comments point towards possible insurgents from the southern provinces of Narathiwat, Yala and Pattani, the scene of an armed conflict between the Thai Army and armed separatist organizations that has taken lives of more than 6,000 people in the last 15 years.
Army chief General Apirat Kongsompong on Tuesday said that the perpetrators of the attacks wanted to undermine confidence at a time when Thailand was hosting regional officials and added that such incidents had also occurred previously during ASEAN meetings, according to the report.
The Army chief's recent comments seem to point to the so-called "red shirts", supporters of former Prime Ministers Thaksin Shinawatra and his sister Yingluck, who were both overthrown in coups in 2006 and 2014, respectively.
( With inputs from IANS )