Police also responded to criticism they were too lenient with detained leaders of the anti-government protests by saying they had now been separated, had their phones confiscated, and were placed under armed guard.
The weapons - including rifles, bullets, grenades and the components of bombs
- were put on display to defend the government's claim that the troops faced a serious threat and exercised appropriate levels of force when they moved in to clear the main protest area.
At least 15 people died in the final offensive Wednesday and more than 100 were wounded.
The Thai capital was gripped with its worst political violence in decades during the so-called Red Shirt occupation of downtown Bangkok, culminating in the military crackdown that sparked a rampage by supporters who launched grenade attacks and set fire to landmark buildings, including the country's stock exchange and biggest shopping mall.
"The fires in many areas in Bangkok were well prepared - step by step," army spokesman Col. Sansern Kaewkamnerd said at a news conference where he was flanked by tables covered with the recovered weapons. Officials said 11 soldiers and police officers were among the 85 people killed in the political violence of the past two months.
Most of the Red Shirts' leadership involved in the protests has either been arrested or surrendered, and many were being held at a seaside police camp south of Bangkok.
The police were slammed after photos circulated on the Internet of the leaders looking relaxed and smiling for group shots soon after in a spacious, well-furnished house on the base that was being used as their holding area.
Police spokesman Prawut Thavornsiri told a news conference police decided to put the leaders in that house because there were not enough rooms elsewhere and the house was more secure.
But following the criticism, Kobsak Sabhavasu, secretary-general to the prime minister, said police officers have now been told to detain the leaders separately and to prohibit them from using communication devices such as cell phones.
Some of the leaders continued to send text messages to supporters and the media for days after they were detained.
The deputy commander of the Metropolitan Police, Umnuay Nimmano, said police cannot imprison the detainees because they have not been convicted of any crimes. But he said the photos were regrettable, and made the detainment look "like a picnic."
Many analysts believe the Red Shirt movement, which supports ousted Prime Minister Thaksin Shinawatra, could foment unrest throughout the country for months or even years to come. Thaksin, who lives in exile after his 2006 ouster in a military coup and subsequent conviction for corruption, has said he supports the Red Shirts' cause.
