"The United States is concerned, but we support the legitimate civilian government of the Republic of the Philippines," US embassy press officer Ron Post told AFP.

Post said Arroyo is the legitimate president of the Philippines.

Arroyo said Saturday her government had discovered a coup plot by junior military officers and warned that they would be severely punished.

Arroyo, a vice president who came to power in a military-led popular uprising in January 2001, said her government was in full control of the situation.

News of the plot followed a week of intense rumors in Manila that a military clique was planning to overthrow the government.

Arroyo had previously dismissed the rumors, saying as late as Friday that she had resolved the legitimate grievances of a group of junior military officers who had complained of low pay, inadequate housing and corruption in the upper ranks.

WAR.WIRE