By Pracha Hariraksapitak and Pairat Temphairojana
BANGKOK (Reuters) - Police claimed significant progress on Wednesday towards finding the mastermind of Thailand's deadliest attack after an arrested man admitted being near the Aug. 17 shrine blast and fingerprints tied him to the room of a suspected bomber.
The unidentified man arrested less than a kilometer from the Cambodian border on Tuesday had told police he was not the bomber, but was in same area the night when a massive explosion killed 20 people.
"It's natural that the suspect will deny he did it, but we still have to continue to look into that," deputy national police chief Chakthip Chaijinda told reporters.
"Right now the case has progressed about 70 percent already."
The latest suspect was "definitely connected" to the attack and had stayed in the same Nong Chok area of Bangkok as another man arrested in a raid on Saturday that found stacks of fake passports, TNT, C4 and fertilizer.
Police have received a torrent of criticism for leading a patchy probe and statements from top officials about possible perpetrators, motives and information extracted from suspects have been contradictory, speculative and often cryptic.
Police spokesman Prawut Thawornsiri said the latest suspect's prints were found on explosives in the same room.
"The man... may be the person who took the bomb out of the room or brought the bomb to the location of the incident," Prawut said on TV.
The investigation has gained momentum since the weekend raids, before which the authorities had little more than a low-resolution surveillance camera video of a man in a yellow shirt leaving a rucksack at the popular Erawan Hindu shrine moments before the blast.
With no claim of responsibility, speculation has centered on sympathizers of Uighur Muslims, opponents of the military government, southern ethnic Malay rebels and foreign extremists.
Thailand's forced repatriation of 109 Uighurs to China in July caused international outrage and saw protesters smash windows and ransack parts of its consulate in Istanbul. Many Uighurs transit through Southeast Asia to try to get to Turkey, which has a large diaspora.
Though many details remain unknown, the probe does appear to have a Turkish connection, with police interrogating the suspects through a Turkish translator and fake Turkish passports seized during one raid.
A wanted Thai woman who rented a room in Min Buri where bomb-making materials were found told police she had been in Turkey with her Turkish partner for months.
Thailand's army chief and defense minister left for a three-day visit to China on Wednesday but said it was a scheduled trip unrelated to the investigation.
It is unclear if Thai police had contacted counterparts overseas for help. Defence Minister Prawit Wongsuwan suggested not.
"This is our own matter, and not theirs," he said when asked if Turkish or Chinese authorities had been consulted.
(Additional reporting by Aukkapon Niyomyat and Panarat Thepgumpanat; Writing by Martin Petty; Editing by Nick Macfie)