Bangkok, Thailand (CNN) -- Thai police said Tuesday that they would seek court permission to extend the detention of a Lebanese man they have charged with illegal possession of explosive materials.
The move comes amid tension after the United States and Israel warned their citizens in Bangkok on Friday of the possibility of an imminent terrorist attack.
The police charged the man, Atris Hussein, on Monday after finding "initial chemical materials that could produce bombs" in an area just outside Bangkok. The police said Hussein, who also holds a Swedish passport, led them to the location.
The authorities are accusing Hussein of trying to attack spots in Bangkok that are popular with Western tourists and say he is believed to belong to Hezbollah, the Shiite Muslim group active in Lebanon that the United States views as a terrorist organization.
Hussein will be brought to the criminal court Tuesday, so that the police can request authorization to continue to hold him as they pursue their investigation, said Piya Uthayo, a police spokesman. The charges of illegally possessing explosives carry a maximum sentence of five years in prison.
Thai authorities said Sunday they were still looking for another suspect of Middle Eastern origin in the case, providing a sketch of his face.
The materials found Monday in Samutsakorn, southwest of Bangkok, included 400 boxes of fertilizers weighing a total of more than 4,000 kilograms and 1,500 liters of liquid ammonia nitrate, together with 400 electric fans, according to CNN affiliate MCOT.
They were found in a shop house, a type of store common in Southeast Asia that gives onto the sidewalk and also serves as the owner's residence.
Based on comments from Hussein, the authorities believe that "Thailand is only a transit point to send these initial explosive materials to other regional countries," said Police General Priewpan Damapong.
A U.S. Embassy statement on Friday spoke of "foreign terrorists" who may be planning attacks "in the near future." It urged U.S. citizens to exercise caution when visiting public areas where large groups of Western tourists gather in Bangkok. Israel issued a similar alert later Friday.
Thailand is a highly popular tourist destination, and Bangkok serves as a major transport hub for the Southeast Asian region.
The country has undergone periods of unrest in recent years. It experienced a spate of political violence during anti-government demonstrations in 2010.
And Muslim separatists in southern Thailand have long battled government forces in a country that is overwhelmingly Buddhist, with a number of bombings taking place last year.