The government has come under criticism for trying to downplay the Bangkok bombing that injured one Iranian suspect and four bystanders.
Democrat Party leader Abhisit Vejjajiva urged the government to come to terms with the fact that the bombs on Sukhumvit Soi 71 and two nearby locations had attracted global attention due to extensive media coverage.
Other countries were watching to see what measures would be implemented to prevent future incidents and ensure public safety but the government was apparently preoccupied with a damage control campaign, Mr Abhisit said.
"Security agencies were sending a message that it was not a terrorist attack because the targets were individuals. But we have to accept the fact that they had bombs and there were attempts to assemble bombs, regardless of what their targets were," he said.
Foreign Minister Surapong Tovichakchaikul had sent the wrong signal to the world when he said the bombers intended to assemble bombs in Thailand for operations in other countries.
This statement could ease fears at home but create confusion in other countries as it could be interpreted that Thailand was not serious about the problem, he added.
"The bottom line is safety for all Thais and foreigners here, and [we must make] an effort not to let the incident jeopardise relations with other countries," Mr Abhisit said.
Panitan Wattanayagorn, a security analyst at Chulalongkorn University, said the government could not deny the suspects planned a terrorist attack.
"No matter what the government says, the picture of a taxi damaged by a bomb sent out to the world by the media and social media speaks for itself that it was an act by terrorists," he said.
Mr Panitan said the government was compelled to tone down the blasts, as admitting it was a terrorist act could scare foreigners away.
"Previous governments also downplayed issues like this. If they admitted a terrorist attack, it will have consequences for Thailand," he said.
Thailand banks on tourism for foreign exchange income, with about 12 million visitors coming to the country last year. The tourism sector accounts for about 6% of gross domestic product.
Mr Panitan called on the government to use this opportunity to revamp its intelligence operations.
The suspects were able to enter Thailand to prepare for their operations without the knowledge of authorities.
"The government must face the truth that we have lax security measures, even though we are a tourist destination," he said.
He also urged the Foreign Ministry to convince the Iranian government to come out to condemn the bombings and show it was not involved.
The four people who lived in the house where the first blast took place, including a woman, carry Iranian passports.
Deputy Prime Minister Yutthasak Sasiprapa told parliament the bombings should not be considered a terrorist plot.
"Evidence shows the targets were individuals, so a terrorist act has been ruled out as of now.
"But all agencies involved are working together to come up with a conclusion to the case," said Gen Yutthasak, who is in charge of security.
He said authorities remained vigilant, as shown by the arrest of suspect Masoud Sedaghat Zadeh at Suvarnabhumi airport hours after the blasts, and prompt cooperation with Malaysia that led to the arrest of another suspect.