MANILA, Dec 31: The Philippine capital Manila awoke to an uneasy calm today, a day after a series of bomb explosions killed 14 people and injured more than 100, reports Reuters.

Traffic was light in the city of 12 million as residents avoided the usual New Year's Eve shopping ahead of the midnight revelry and feasting, one of the biggest celebrations of the year in the Roman Catholic nation and marked in the streets by gunfire and fire crackers.

Police said they still had no clues who was behind the five bomb explosions which rocked the city on Saturday. At least three people have been taken in for questioning but police superintendent Avelino Razon said there had been no breakthrough.

Opposition leaders said the bombings may have been the work of pro-government agents in a bid to force the declaration of an emergency or martial law and halt proceedings in the impeachment trial of President Joseph Estrada.

The trial, in which Estrada has been charged with corruption and bribery, is going against the president, analysts have said. Proceedings resume on Tuesday after the holiday recess.

Asked if the attacks would force him to declare martial law, Estrada told reporters: "I don't believe so, not yet that's still far off."

He has declared a full alert and ordered the police and military to hunt down the assailants.

Four of the bombs went off almost simultaneously around noon (1000 BST) on Saturday. A fifth exploded some two hours later wile it was being defused by bomb squad officers.

The most devastating explosion was in the front coach of a suburban train as it was pulling into an elevated station.

At least 11 people were killed and more than 60 injured. Other blasts were on a public bus and in an airport warehouse.

"The bombs have changed the nature of the political crisis," political analyst Alex Magno said

in a television interview. "For three months we have gone through this crisis without any violence."

The government has said the explosions might have been carried out by the Muslim rebel group, the Abu Sayyaf, or by communist guerillas.

A brother of Abu Sayyaf leader Khadafy Janjalani was arrested in Manila earlier this week and police found drugs and weapons in his possession.

But communist groups have denied responsibility and many police officials have said Muslim rebels do not have the capability to mount such an assault. The Muslim rebel groups operate mostly in the south of the country.

"If not the (Muslim groups or the communists) then who?" columnist Rigoberto Tiglao said in the Philippine Daily Inquirer. "A group with military capability and training certainly. The masterminds could only be a cabal with access to such a group.”