The Philippines has placed its entire military and police force on their "highest" security alert level to head off possible terrorist attacks on over 7,000 world leaders and delegates gathering in Manila for next week's Apec summit.

"We are on highest alert (for Apec)," said Mr Marciano Paynor, head of the Apec organising council, following attacks in Paris that reports say have left about 150 dead.

Foreign Ministry Undersecretary Laura del Rosario told Agence France-Presse the attacks would mean "higher security" around and near Apec-designated venues and hotels.

"Our security officials are monitoring and asessing the situation, and are taking necessary precautions to ensure the safety, security, and well-being of all delegates," the Foreign Ministry's spokesman Charles Jose said in a text message.

Over 20,000 policemen, soldiers, firemen, and rescue, emergency and first-aid workers have been enlisted to help secure 17 heads of state who will be attending the Apec Economic Leaders Meeting on Nov 18 and 19, including United States President Barack Obama and Chinese President Xi Jinping.

President Vladimir Putin of Russia and President Joko Widodo of Indonesia have sent word they were skipping the summit - set to be held on Nov 16 to Nov 19 - to attend to pressing domestic concerns.

With dry runs held since early this morning (Nov 14), Manila is already on lockdown.

At least two major highways are being closed to traffic.

The capital is on a weeklong holiday, and the skies over the capital will be a no-fly zone for three days next week.

Chief Superintendent Wilben Mayor, spokesman of the Philippine National Police (PNP), told reporters the nation's entire police force is now on "red alert", two days earlier than planned, because of what was happening in Paris.

He said security officials were now keeping a closer watch on key installations and along "peripheries" of metropolitan Manila, home to over 11 million.

PNP Director for Operations, Jonathan Miano said in a news briefing that there has so far been "no information, direct information, that there's a threat from terrorist groups".

"The only threat that we expect are the threats from the rallyists… So far, that the only information we have. From other threat groups, we have none," he said.

Leftist groups are planning rallies to protect, among others, a military pact between the Philippines and the United States, China's actions in the South China Sea, and Canada's dumping of garbage in the Philippines.

President Benigno Aquino, meanwhile, joined other world leaders in condeming the Paris attacks.

"We stand with France now, in the firm belief that the light must never dim in Paris," said Mr Aquino.

He said the Philippines "stands in solidarity with the people of Paris and all of France, in this time of deepest sorrow and the gravest outrage against the perpetrators of these crimes".

The attacks demand "a united voice from the world in condemnation and grief", he said.

Mr Aquino also assured that "there is no credible threat registered at this time, but let us all be cooperative and vigilant".