United Nations Conference on Trade and Development (Unctad) Secretary-General Supachai Panitchpakdi on Thursday encouraged Thai government to impose more stringent immigration controls after Tuesday's blasts in Bangkok, the online edition of Bangkok Post newspaper reported.

He was speaking on the sidelines of an International conference in Bangkok on "The Meaning of Sufficiency Economy."

He said violence and terrorist activity were occurring elsewhere and Thailand might want to be more careful on immigration control policy.

The three explosions in central Bangkok on Tuesday reflected increasing global tensions, but Thailand had to stand firm in saying that this is not a problem stemming from its own affairs.

"Our security is sufficient and we have to show the world that we are ready with preventative measures now and when needed," he was quoted as saying.

The United States has imposed strict immigration measures after the Sept. 11 attacks and other countries also saw the necessity to take similar steps.

Supachai encouraged analysts and the media to clearly explain to the Thai public that Thailand was part of the global society and not immune to violence, so the country should not take risks but rather take more precautions.

On Tuesday, three consecutive blasts occurred in downtown Bangkok, injuring five people. Thai police have issued arrest warrants for four Iranian nationals on charges related to the blast.