BANGKOK: Thai authorities said Thursday international terror groups were likely not behind a deadly Bangkok shrine bombing, but appealed for Interpol help in tracking down a young “foreign” man suspected of planting the device.

Police also said that the attack on a Hindu shrine in a bustling tourist hub of the capital was carefully planned by a network of more than 10 people.

Monday’s blast killed 20 people, mostly Asian visitors, leaving residents and even the military junta leader fearing more attacks, while sending shockwaves though the nation’s vital tourism sector.

The apparent deliberate targeting of tourists and the scale of the explosion had never been seen in the Thai capital and, with no-one claiming responsibility, experts were perplexed over who to blame.

Thailand’s national police chief, Somyot Poompanmoung, on Thursday gave the most detailed profile of the mysterious assailants, saying there were more than 10 involved and that they had carefully planned it.

“This blast was carried out by teams ... there was a survey team, a protection team, material providing team and exit team,” Somyot told reporters.

But after days of confusing and sometimes contradictory information from Thai authorities over their investigation, they also said they did not believe global terrorist organizations were involved.

“Security agencies have collaborated with intelligence agencies from allied countries, and have come to the same preliminary conclusion that the incident is unlikely to be linked to international terrorism,” junta spokesman Col. Winthai Suvaree said in a televised update.

Winthai also said: “Chinese people were not the direct target.”

This appeared to be aimed at countering accusations run by some sections of the Thai media that militants representing the ethnic Chinese Uighur minority had carried out the attack.

Thai police said they still did not know if the man suspected of planting the bomb at the shrine minutes before the blast was in the country or not, as they asked Interpol for help.

An arrest warrant was issued for him on Wednesday after police also released a sketch showing him in glasses and with dark hair, describing him as a tall foreigner with fair skin.

The sketch depicted generally ambiguous features that made it hard to determine his ethnicity.