Thai police have awarded themselves a £54,500 reward for making an arrest in the Bangkok bombing investigation.

The reward was originally offered to the public for tips leading to the arrest of suspects, but national police chief Somyot Poompanmoung said he was taking the unusual step of redirecting the cash to highlight that Thailand's police are good at their job.

The decision added to criticism over police handling of the investigation into the August 17 bombing at Bangkok's Erawan Shrine, which killed 20 people and injured more than 120.

Mr Somyot made the announcement at a news conference, saying he had "good news".

"Give me the bag," he said, turning to an aide who handed over stacks of cash.

"This is real money," the police chief said. He added that Saturday's arrest was thanks to "good police work" and had not come from any outside tips.

"It is the ability of Thai officials that led to the arrest," he said. "This money should be given to officials who did their job."

Police made a potential breakthrough on Saturday when they arrested a man in the outskirts of Bangkok and found bomb-making material including detonators, ball bearings and a metal pipe at his apartment.

They found more bomb-making materials on Sunday in a raid on another apartment in a nearby neighbourhood.