MANILA - Two colonels and six special forces soldiers were being detained and questioned in connection with an alleged conspiracy to overthrow President Gloria Macapagal Arroyo.

Arroyo, who survived a crisis last year over accusations of vote-rigging and graft, invoked emergency rule for a week before lifting it last Friday after security chiefs said the threat had eased and investors warned of damage to economic reforms.

The military has said agitators continue to try to recruit soldiers to join the alleged plot against Arroyo by communist groups, some of her political enemies and rogue troops.

A senior army official said that seven of the eight officers and junior officers in detention were members of the elite Scout Rangers regiment, whose commander Brigadier-General Danilo Lim was removed during the brief state of emergency.

The soldiers are accused of planning to join Lim and 17 other Scout Rangers at anti-Arroyo rallies on February 24 in a bid to spark unrest in the crowd by withdrawing support for the president.

"They are under restrictions while awaiting the recommendations of the inspector general," said the army official, who declined to be identified.

Two Marine commanders and four top officials of the police's elite unit have also been removed and face investigation.

Five leftist lawmakers wanted for questioning remained holed up in Congress, waiting for police to produce arrest warrants.

A sixth member of Congress has been in custody since February 25, a day after Arroyo declared emergency rule.

Intelligence officials have linked other opposition figures and religious leaders to the plot.

Arroyo, due to complete her term in 2010, has been at pains to show that it is business as usual in the Philippines while trying to convince Filipinos and foreign investors there really was an organised move to set up a civilian-military junta.

Lim, the Scout Ranger general implicated in the plot, denied he was part of a coup attempt.

"It is not true that I am involved in an alliance with the left. I will never allow myself to be in that position," he said.

Critics and analysts suspect Arroyo's government of playing up parts of the conspiracy, especially the leftist threat, to allow the military a more free hand to fight a long-running communist insurgency and crack down on the president's foes.

Groups of journalists have filed a petition in the Court of Appeals to halt what they said was a state chill on the media, which the president accused of contributing to instability.

The publisher of the Daily Tribune and two columnists face sedition charges after police raided the opposition newspaper.

Troops had also kept watch for a week over two television stations, a move criticised as a reminder of nine years of martial law under the late dictator Ferdinand Marcos.

"The threat of official intervention -- in the form of administrative sanction or criminal prosecution -- is just as damaging to a free press as the fact of it," the petition said.

On Tuesday, the Supreme Court began hearing arguments over seven petitions seeking to have Arroyo's emergency rule declared unconstitutional and set down a precedent for future cases.