Thai police say the fingerprints of a foreign man arrested at the border with Cambodia match those they found on a bottle containing bomb-making material.

The bottle was among many items seized during a raid on Saturday of a flat on the outskirts of Bangkok where another suspect was arrested as part of the investigation into the deadly August 17 bombing at the Erawan shrine.

Both suspects are being interrogated by the military and have not yet been charged.

National police spokesman Prawut Thavornsiri said that the man arrested at the border on Tuesday "is important and is related to or conspired with people" behind the bombing that killed 20 people and wounded more than 120.

The investigation into the attack has picked up in recent days with the arrest of two suspects and raids on two apartments on the outskirts of Bangkok that contained bomb-making materials.

In the first apartment, raided on Saturday in the Bangkok neighbourhood of Nong Chok, police arrested a suspect they described as a foreign man and seized bomb-making equipment that included detonators, ball bearings and a metal pipe believed to be a bomb casing.

They also took fingerprints from the apartment, which turned out to match those of another suspect arrested on Tuesday at the border with Cambodia, Mr Prawut said.

"We can confirm that the man's fingerprints match with those found on a bottle that contains a bombing substance," he said, adding: "He could be the one who brought the bomb out of this apartment or he could have brought the bomb to the crime scene."

Mr Prawut said further testing, including DNA tests, were being conducted to bolster that theory.

When authorities announced the arrest of the suspect at the border, they described him as bearing a resemblance to a man spotted in surveillance video at the shrine who is believed to have planted the bomb. The suspect in the video, wearing a yellow T-shirt, is carrying a backpack that he places on a bench before leaving.

Prime minister Prayuth Chan-ocha told reporters that the arrested man is a foreigner who appeared to be trying to escape across the border.

No one has publicly claimed the attack, sparking an array of theories about who might be behind it.

Speculation has grown that the suspect might be part of a group seeking to avenge Thailand's forced repatriation of ethnic Uighurs to China in July. Mr Prayuth on Monday linked the two theories, suggesting the bombers might have been involved in smuggling Uighurs out of China.

The prime minister said officials knew from their investigation that people involved in the bombing were about to flee the country and had traced one of the suspects to Aranyaprathet district in Sa Kaeo province, a crossing point to Cambodia. He described the man as a piece in a jigsaw puzzle that would connect various parts of the case, which included a bomb that exploded harmlessly in a river next to a busy pier in Bangkok the day after the shrine blast.

Mr Prawuth said on Tuesday that three new arrest warrants had been issued in connection with the case, bringing the total to seven. Two were named persons - he could not provide spellings for the names of the men, whose nationalities were unknown - while the third was not identified by name but was described as a Turkish national. He displayed pictures of the three on a computer.

Uighurs are related to Turks and Turkey is home to a large Uighur community. The Erawan Shrine is especially popular with Chinese tourists, feeding the idea that it could be a target for people who believe the Uighurs are oppressed by China's government.

Beijing says some Uighurs are Islamist terrorists, and that among them is a group that has been smuggled out of China to join Islamic State fighters in Syria.

Thailand's national deputy police chief, Chakthip Chaijinda, told reporters the suspect arrested at the border speaks Turkish, which requires a translator.