Thailand has asked Interpol for help in tracking down the man they believe planted a bomb in Bangkok that killed 20 people, the Reuters news agency reports.

The military government was initially reluctant in asking for outside help in the investigation of the blast at a famous shrine on Monday evening that killed 20 people and wounded scores.

However, it has now sent the international police organisation an image of the suspected bomber.

“We sent a request for assistance,” Kissana Phathancharoen, deputy national police spokesperson, told Reuters.

There has been no claim of responsibility and police have not determined a motive for the worst ever bomb attack in Thailand.

The attack left at least 11 foreigners dead, with Chinese, Singaporeans, Indonesians and a family from Malaysia among the victims.

More than 100 other people were wounded by the blast that shredded bodies at one of the city’s busiest intersections.

Thai military spokesman Colonel Winthai Suvaree said on Wednesday that the bombing was “unlikely to be linked to international terrorism.”

He also said that Chinese tourists, who were among the victims, were not the “direct target.”

Grainy footage

Police suspect the young man caught in grainy footage leaving a backpack at the crowded shrine shortly before the explosion is foreign but Kissana said Thai police were not focused on any particular country or region with their appeal to Interpol.

“We basically sent in the modus operandi [of the suspect] and also the appearance of the suspect we’re looking for,” Kissana said.

Somyot Poompanmoung, a senior police officer, said on Wednesday that the attacker did not carry out the attack by himself, without elaborating further.

He made the comment as he headed into a meeting of national police commanders, adding that he was carrying orders from the prime minister who “is worried about the security of people and tourists in Thailand”.

“He didn’t do it alone, for sure. It’s a network,” Poompanmoung told the Associated Press news agency.

Police say two other suspects were also identified in CCTV footage of the blast site.

Officials various times said that they did not rule out any group, including elements opposed to the military government, though they said it did not match the tactics of Muslim fighters in the south or “red shirt” supporters of the previous administration.

On Tuesday, the police released grainy closed-circuit television (CCTV) footage of a young man wearing a yellow T-shirt.

Information wanted

Police say the sketch could help locate the yellow-shirted man seen in the CCTV footage. A 1 million baht ($28,000) reward has been offered to anyone who can give police information leading to his arrest.

On Wednesday, Buddhist monks led prayers for the reopening of a Bangkok shrine located in busy Ratchaprasong commercial district.

A small explosion on Tuesday by a bridge at the city’s Chao Praya River has been tied to Monday’s bomb.

Colonel Kamthorn Ouicharoen, of the Thai bomb squad police, confirmed the bridge bomb was the same type as the one detonated at the Erawan shrine.

Thailand has experienced a near-decade long political crisis that has seen endless rounds of street violence, but never anything on the scale of Monday’s bomb.

Al Jazeera’s Scott Heidler, reporting from Bangkok, said the bombings came just as tourism is rebounding in Thailand.

“The arrival numbers of the all-important Chinese market doubled for the first half of this year compared to the same period last year,” he said.

About 10,000 additional security forces have been deployed in Bangkok after the bombing, reassuring some tourists.

“At first I was shocked to hear about the blast. After assessing the situation, I think Bangkok might be safer after the bomb,” one Chinese tourist told Al Jazeera. Al Jazeera