Thai police said Monday they were seeking two new suspects — a Thai woman and a foreign man of unknown nationality — in the widening investigation into Bangkok's deadly bombing two weeks ago.

In a televised statement, police released a photograph of the woman's Thai identification card — showing a young woman in a black headscarf — and a sketch of the man whose nationality was unknown.

The development came after police arrested a man from an apartment in Bangkok's outskirts on Saturday and seized bomb-making equipment that included detonators, ball bearings and a metal pipe believed to be a bomb casing. More bomb-making materials were found in a second apartment during a raid Sunday in a nearby apartment.

National police spokesman Prawuth Thavornsiri said Monday the second apartment that was raided, in a neighborhood known as Min Buri, was rented by the Thai woman, who is being sought. They identified the woman as Wanna Suansun and said she was 26 years old.

He said the man is believed to have lived in the apartment, where police found fertilizer, gun powder, digital clocks and remote-controlled cars whose parts can be used for detonation, among other items, Prawuth said.

"These are bomb-making materials," Prawuth said. "Nobody would keep urea fertilizer and gunpowder unless they wanted to make a bomb."

Saturday's arrest 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 others.

Much remains unknown about the suspect, including his nationality, his motive, his relationship to the alleged bombing network or if he was plotting an attack, Prawuth said, adding that another attack was "possible" because police found 10 detonators.

"We still have to work out the details," he said. "But we are very certain he's part of the network" that carried out the bombing.

On Sunday, Prawuth said police were working with "a number of embassies" and interpreters to try to establish the man's nationality, adding that he did not speak Thai but spoke some English.

Authorities have dodged questions about whether the suspect is believed to be Turkish, saying that he was traveling on a fake passport. Images circulated online after his arrest of a fake Turkish passport with the apparent suspect's picture.

The Turkish Embassy in Bangkok could not immediately be reached for comment. A Turkish government spokesman contacted over the weekend in Istanbul said he had no information on the suspect or any possible Turkish link to the attack.

The blast at the Erawan Shrine was unprecedented in the Thai capital, where smaller bombs have been employed in domestic political violence over the past decade, but not in an effort to cause large-scale casualties.