BANGKOK - The Thai army has denied speculation that the small explosions at a shopping mall in the capital over last weekend were an attempt by the government to prolong martial law.

Army commander Udomdej Sitabutr told the Bangkok Post that the state would never create such situations, and that they "do things honestly".

His remarks came as the city police were trying to identify two men seen in a security-camera footage outside Siam Paragon shopping mall shortly before two pipe bombs exploded there Sunday night, The Nation reported.

Video experts are trying to magnify faces of the suspects who were seen wearing t-shirts and caps.

The army has also said three groups are under suspicion for the two explosions, while police said they are "90 per cent certain" the attack is politically motivated.

The three groups are those affected by the National Council for Peace and Order's (NCPO) crackdown on bribery, extortion and corruption; the political group dissatisfied with the military government; and police officers who are displeased after recent transfers.

Two homemade bombs had exploded on Sunday, sparking panic among shoppers and tourists. Two people were injured. Police initially reported the blasts were caused by a transformer explosion, but later revealed they were caused by two pipe-bombs hidden behind an electrical control panel.

Police and the military said the bombs were low-impact devices and could not have caused loss of life.

Prime Minister Prayut Chan-Ocha Tuesday condemned the blasts and urged the public to give authorities enough time to solve the case.