Thai police say the man arrested in connection with Bangkok's deadly bombing was being uncooperative and appeared to be lying during questioning and would remain in military custody for at least seven days.

National police spokesman Prawuth Thavornsiri said Sunday that authorities "think he is not telling us the truth."

The unnamed foreigner was arrested Saturday after police raided an apartment he was in where they found bomb-making equipment and fake passports.

It was the first possible breakthrough in the investigation into the Aug. 17 blast at the Erawan Shrine, which killed 20 people, more than half of whom were foreigners, and injured more than 120 people.

Prawuth said his nationality and motive were still not known.