A Thailand police spokesman has unequivocally stated the man in a yellow t-shirt seen in security footage at the bomb site before the blast, is the person responsible for the attack.

“The yellow-shirt guy is not just the suspect. He is the bomber,” Lt Gen Prawut Thavornsiri, a police spokesman, told Associated Press.

Earlier, Thailand’s junta chief Prayuth Chan-ocha said authorities are hunting the “suspect” seen on CCTV footage near the scene of a bombing that claimed at least 22 lives in Bangkok and wounded scores more.

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“Today there is a suspect who appeared on CCTV but it’s not clear… we are looking for this guy,” General Prayuth said at Bangkok’s Government House.

“I have ordered the cameras be checked.”

Meanwhile, police reported a second explosion in Bangkok on Tuesday afternoon, with no injuries, a day after the deadly bombing.

The second explosion occurred at a ferry pier, but this time no one was hurt, police say.

Police Senior Sergeant Major Worapong Boonthawee said an explosive device was thrown from the Taksin Bridge and blew up at Sathorn Pier after falling into the Chao Phraya River below.

Security camera footage showed a sudden blast of water dousing people on a walkway at the pier, as bystanders ran for safety.

General Prayuth said the suspect in the first bombing was believed to be from an “anti-government group based in Thailand’s north-east” — the heartland of the kingdom’s anti-coup Red Shirt movement.

General Prayuth, who is also the Thai prime minister, said the bombing, at a religious shrine popular with tourists, was the country’s “worst ever attack”.

Eleven of the 22 victims in the bombing were from countries including China, Hong Kong Singapore and Malaysia, but no Australians were reportedly among the dead.

Prime Minister Tony Abbott has urged Australians to continue travelling to Thailand, despite Monday night’s bombing.

“Attacks such as this only strengthen the resolve of the Government and the people of Australia … and the Parliament of Australia, to do whatever we can to counter extremism and combat terrorism,” Mr Abbott said.

Mr Abbott says Australia has offered Thailand assistance.

Red Shirts bringing Bangkok’s clashes to the tourists?

Since 2006, Bangkok has witnessed repeated rounds of deadly political violence, flanked by two coups.

Until Monday though, foreigners had rarely been caught up in the bloodshed.

Debris after the bomb blast in downtown Bangkok. Photo: Getty

The most recent coup in 2014 toppled the elected government of Yingluck Shinawatra after months of disruptive street protests.

Thailand is also fighting a decade-long insurgency in its southernmost Muslim-majority provinces that border Malaysia, which has seen more than 6,400 people killed, mostly civilians.

General Prayuth’s comments suggest the investigation is shifting towards anti-government groups loyal to the ousted Shinawatra family, rather than the southern Muslim militants.

The Red Shirts are a grassroots network of the rural and urban poor, particularly from the country’s north-east, that support Yingluck and her ousted prime minister brother Thaksin Shinawatra.

Authorities have blamed them for a string of small explosions in Bangkok earlier this year, a charge their leadership has strongly denied.

They were also initially blamed by authorities for a car bomb on the resort island of Koh Samui earlier this year, but police were later forced to backtrack and subsequently blamed insurgents for that attack.

While hardcore Red Shirts have been known to launch attacks on security forces or government buildings, they have never before carried out a mass casualty bombing.

Thailand’s Islamist insurgents are also not know to target foreigners and have also largely kept their violent attacks to the three Muslim-majority provinces in the country’s south.