The investigation into the Bangkok bombings is making progress and more suspects have been arrested, Deputy Prime Minister Prawit Wongsuwon said on Tuesday, but remained vague on the details.
The army chief was more direct, linking the attack to past violence aimed at embarrassing the government during previous meetings of the Association of Southeast Asian Nations (Asean) in Pattaya and Phuket.
The bombers came from southern border areas, but investigators had yet to establish if the attack was politically motivated, Gen Prawit said in response to reporters' questions at Government House.
"Many people launched this incident. We must find out how they travelled here and where their materials came from," the deputy prime minister said.
Army chief Gen Apirat Kongsompong said the masterminds of the Bangkok bombings last week were people who disobey the rules.
"They wanted to undermine confidence at a time when the country was hosting meetings of Asean leaders. We have seen such incidents during previous Asean meetings in Pattaya and Phuket, and there was also an attempt in Hua Hin. I was there," Gen Apirat said.
A series of small bombs were detonated, and fires were started, during the Asean Foreign Ministers' Meeting in Bangkok last week. A violent anti-government red-shirt protest shut down the Asean Summit in Pattaya in April 2009, with visiting ministers being evacuated by helicopters and boats.
"The same old group that was the mastermind wants to create all kinds of unrest," Gen Apirat said.
The incidents were aimed at discrediting the government, but it was hard to nail the masterminds.
