By Alasdair Sandford | With REUTERS

Thailand’s authorities are looking for a suspect seen on CCTV footage at the scene of the Bangkok bombing that killed 22 people and injured 123 others.

Shortly before Monday’s blast the young man in a yellow T-shirt was seen taking off his backpack close to the Erawan Hindu shrine where the bomb went off.

He then left the scene apparently checking his phone – but without the pack.

No group has claimed responsibility for the attack.

Fraying nerves still further in the Thai capital, Tuesday saw another explosion – but one which caused no deaths or injuries.

An unidentified man threw the explosive near a busy pier on the city’s Chao Phraya river and it landed in a canal, said Colonel Natakit Siriwongtawan, deputy police chief of Klongsan district.

“If it did not fall in the water then it certainly would have caused injuries,” he said.

Possible links with Monday’s attack are being investigated.

As investigators into the first, fatal explosion combed the scene around the Erawan shrine on Tuesday the national police chief said the suspect could be Thai or foreign.

Nearly half of the dead were foreigners. Thailand’s military government believes the attack was aimed at destroying the economy, which relies to a great extent on tourism.

“Yesterday I was at the explosion last night maybe 50 metres (yards) away. I heard the big bang and I looked back and I see people screaming and I started running,” said Australian tourist Durian Rider.

“The family sent me messages asking if everything was okay because they heard of that and yeah I am okay, but it is very scary. Something very dangerous happens to people and nobody knows who it was, so yeah it’s scary,” said Mirjam Rodehacke from Switzerland.

Some reports quoted Prime Minister Prayuth Chanocha as saying the suspect was believed to belong to an “anti-government group based in Thailand’s northeast”. Thai media later said the quote was not referring to the suspect.

Thailand has experienced years of political violence, with a military junta taking control of the country in May after ousting the government of Yingluck Shinawatra. Until Monday, however, foreigners had rarely been caught up in the trouble.

Suspicions have been cast on Muslim insurgents in the south, and on Uighurs angry at the expulsion of refugees back to China. But there is scant evidence for such theories and some experts have expressed doubts that the attack is linked to domestic politics.