BANGKOK Thai Prime Minister Thaksin Shinawatra was cleared Friday of asset concealment charges that threatened to force him out of office just six months after a landslide election victory.

In a surprise decision, the Constitutional Court's 15-member panel voted by a slim majority to find Thaksin not guilty of the charges that he deliberately filed a false assets statement four years ago.

"The prime minister was found not guilty ... in a vote of eight to seven," said Court President Prasert Nasakul.

"The majority of the judges decided ... that Thaksin did not intend to conceal the assets," said another judge, Ura Wang-Orm-Glang.

The court found that the National Counter Corruption Commission (NCCC) failed to prove that Thaksin was aware of extensive shareholdings held under the names of his household servants.

"Evidence and witnesses presented by the NCCC did not prove that Thaksin had any knowledge of his wife's organization of nominee shareholdings," it said in a statement.

The NCCC acted as prosecutor in the historic Constitutional Court trial which ended in mid-June.

Financial markets rallied at the news of the acquittal, with the stock exchange of Thailand's main index closing 12.72 points, or 4.2 percent, stronger at 315.95 points.

The prime minister would have faced a five-year ban from office if the Constitutional Court had found him guilty of concealing part of his huge personal fortune in the statement filed when he served as deputy premier.

The judges had been widely expected to find Thaksin guilty, but in a compromise move to backdate the ban to the date of the alleged offence, leaving him with just over a year to serve on the political sidelines.