Thai police have released a detailed sketch of the man suspected of planting the bomb. Photo taken from BBC.

The authorities believe that bomb blasts at the Erawan shrine and Sathorn Bridge in Bangkok this week were aimed at discrediting the military government in Thailand, national police chief General Somyot Poompanmuang has said.

A number of bomb hoaxes were reported at various locations in the capital yesterday.

The National Police Office is now offering up to $84,000 (Bt 3million) for a tip-off leading to the arrest of the man suspected of planting the bomb at the Erawan Shrine on Monday evening.

This is in addition to a $56,000 (Bt 2million) reward that former prime minister Thaksin Shinawatra has offered, according to a Facebook post by his son, Panthongtae. Moreover, Panthongtae said his father would provide another $140,000 (Bt 5million) to officials who would contribute to the arrest, if made.

National Council for Peace and Order spokesman Colonel Winthai Suvari, meanwhile, announced that several agencies believe the blasts were intended to seriously hurt the economy and tourism.

He said inquiries into the blasts were progressing. “But the authorities cannot release details at this point, as that may affect ongoing investigations,” he said.

A Thai military policeman patrols with military dog 'Ken', which has a camera mounted on his back, as they inspect elephant statues at the Erawan Shrine, in central Bangkok, Thailand, 20 August 2015. The Erawan shrine reopened to the public on 19 August. Photo: THE NATION

A sketch of the suspected bomber at the Erawan Shrine was released on Wednesday but immigration officials have not spotted him at any checkpoint.

Monday’s blast killed 20 people and injured more than 100. The Sathorn Bridge blast did not cause any casualties as it exploded in water near the Chao Phraya River.

The government is considering the option of providing higher compensation to the victims.

Prime Minister Prayut Chan-o-cha yesterday urged the public to be eyes and ears for soldiers and police in a bid to ensure public safety and he called on people to quickly inform the authorities if they see anything suspicious.

However, he said people should not be fearful of the situation to the extent that they stay at home and do not spend money because that would hurt the economy. Several other countries had faced similar security situations or much worse but their people lived normal lives, he said.

“This is our home and country, so don’t allow outsiders to play an excessive role. We ought to chart our own future, but we also have to listen to outsiders’ voices,” he said.

The premier said foreign countries have offered to help the authorities such as the US, which has sophisticated technology that would help with the investigation, especially in terms of identifying a suspect captured on CCTV.

Meanwhile, police yesterday found a suspect package at Benjakiti Park on Ratchadaphisek Road next to Queen Sirikit Convention Centre. When the package was unwrapped, a brand-new rattan ball and sand were found inside, creating the impression it might have been a bomb and causing panic. A suspicious bag was also found near the Metropolitan Police Bureau. Police said they would summon the taxi driver who left it there for questioning. The owner of the bag told police he accidentally left it in the cab.

Education Ministry permanent secretary Dr Kamjorn Tatiyakavee revealed that an unknown man phoned the ministry and claimed that something bad would happen there.

“Now, we have stepped up security at the ministry compound,” he said. “Someone might have wanted to spread a climate of fear.”

In related news, examination of CCTV footage has revealed a possible suspect in the Sathorn Bridge attack. Long-distance footage shows the potential suspect walking towards the pier under the bridge on Monday evening – the night before the attack – carrying a plastic bag that could have contained an explosive.

The man kicked the bag into the river around 7.30pm, about half an hour after the Erawan Shrine explosion. He wore a blue shirt and trousers and may not have intended to cause casualties as the bomb exploded in the water.

Police said the suspect could be Thai.

Message of condolence

Their Majesties the King and the Queen have sent condolence messages to the heads of state of four countries, expressing deep sorrow especially to the families of those killed in the bomb blast at the Erawan Shrine in Bangkok. Twenty people were killed and more than 100 injured. Fourteen of those killed came from China, Singapore, Malaysia and Indonesia.