Buddhist monks have led prayers for the reopening of a Bangkok shrine where a blast killed 20 people, as police in Thailand continue to hunt a man shown on security footage calmly planting what is believed to be the bomb.

The bomb struck early on Monday evening as worshippers and tourists crowded into the Erawan shrine in the Thai capital's commercial heart, but no one has yet claimed responsibility.

About a dozen monks led the prayers at the Erawan shrine as it reopened early on Wednesday while devotees - including tourists - bent down and held joss sticks.

The attack left at least 11 foreigners dead, with Chinese, Hong Kong, Singaporean, Indonesian and a family from Malaysia among the victims.

The photos of the suspect released [Reuters]

More than 100 other people were wounded by a blast that shredded bodies and incinerated motorcycles at one of the city's busiest intersections.

Police said a second explosion at a Bangkok pier on Tuesday that caused no injuries may be linked, deepening fears for Bangkok residents with police conceding they do not know who was responsible.

A relative of the dead Malaysians had laid bundles of clothes at the shrine to represent the lost loved ones, according to a monk.

The shrine - a popular tourist attraction that typifies the kingdom's unusual blend of Hindu and Buddhist traditions - and its surrounding had already been largely restored.

Twisted iron railings were the only immediate sign of the carnage, which police believe was caused by a bomb made up of three kilogrammes of explosives and ball bearings.

Suspect's images

Police released images on Tuesday showing a man, apparently young, slightly built and wearing a yellow T-shirt and dark shorts, walking into the shrine with a backpack.

In the video he calmly places the backpack underneath a bench and then walks away clutching a blue plastic bag and what looks like a smartphone.

The bomb exploded several minutes later, leading Thailand police to make the man their prime suspect.

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.

"It's exactly the same, the equipment used to make it, the bomb size," he said.

"Police will resume collecting evidence this afternoon," he said.

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.

A long-running insurgency by Muslim fighters in the Thai south has claimed 6,400 victims, but is a highly localised conflict.

Source: Al Jazeera and agencies