By Aukkarapon Niyomyat and Amy Sawitta Lefevre
BANGKOK (Reuters) - Thai government officials and police chiefs attended a religious ceremony on Friday for the victims of the country's worst ever bombing but appeared no closer to determining who carried out the attack and why.
The only solid evidence seems to be grainy security camera footage showing an unidentified young man apparently planting a backpack bomb at the Erawan shrine, one of Bangkok's top tourist attractions, on Monday evening.
Twenty people were killed, 14 of them foreigners, including seven from mainland China and Hong Kong.
Officials have speculated that the young man, last seen on video footage disappearing into the night on the back of a motorcycle taxi, could be foreign, or a Thai man pretending to be foreign.
Initial speculation that the plot could be the work of an international terror network has for now been set aside.
And on Friday, police chief Somyot Pumpanmuang appeared to back-track on his suggestion the previous day that the bomber was probably part of a network of at least 10 people who spent a month planning the attack.
"We still have no information on international terror groups and think that there is no link to international terrorism," Somyot told reporters after attending the multi-faith prayer ceremony outside a shopping center across from the shrine in central Bangkok.
"What is clear is that it was intended to discredit the government, destroy confidence and make tourists scared and not travel to Thailand," he told reporters.
The Erawan shrine, dedicated to a Hindu deity, is hugely popular with tourists from China.
The government has said Chinese tourists were not believed to have been the target. Announcements about the investigation have been broadcast in both Mandarin Chinese and English.
Asked about his suggestion that 10 plotters were probably involved, Somyot said there might only have been two.
Deputy Prime Minister Prawit Wongsuwan was among the hundreds who took part in the ceremony to pray for the dead. Scores of people were wounded in the blast.
(Editing by Robert Birsel and Dean Yates)