MANILA, Philippines ? (UPDATE 2) The Philippines went on high alert Thursday as a ?super typhoon? threatened to unleash more devastation for millions of people already struggling to recover from deadly floods that claimed 277 lives.

?Pepeng? (international codename: Parma) was gaining strength as it churned towards the Southeast Asian nation and was expected to dump more heavy rain on areas still reeling from the weekend floods that forced nearly 700,000 people into evacuation camps.

"We are dealing with a very strong typhoon, so we should be at the highest level of preparedness," weather bureau spokesman Nathaniel Cruz said, amid forecasts the typhoon would make landfall on Saturday.

"There is a possibility that this will become a super typhoon," Cruz said.

The government defines a super typhoon as one with winds reaching 175-200 kilometers per hour (110-125 miles per hour) with the potential to cause heavy damage.

"Keep glued to the radio and TV, prepare for the strong rains and let's all pray... let's hope it doesn't become stronger," Cruz, Pagasa deputy director for operations, told a press conference on Thursday.

Cruz said there was an 80-percent chance "Pepeng" would become a super typhoon. "This is a very strong typhoon. It is not a joke... This could be a super typhoon in the next 24 hours," Cruz said Thursday.

The Pagasa official said that if it maintained its present course, "Pepeng" was expected to make landfall in the Aurora-Isabela area in Northern Luzon by Saturday morning.

Cruz said that even if the typhoon hit land by Saturday, it was unlikely to weaken.

He said large parts of the eastern side of Luzon and the Visayas could experience heavy rains even before Saturday because of the typhoon?s effects could be felt over an area stretching 250 kilometers from its eye or center. These include Isabela, Aurora, Quezon, the Bicol Region and Samar which, he said, would experience heavy rains by Thursday evening.

Pagasa weather forecaster Robert Sawi said Pepeng could strengthen in the next 24 hours because it was still over the sea.

Cruz said large parts of Luzon could experience heavy rains, especially the Aurora-Isabela area where the eye of Pepeng is expected to touch land.

"Saturday is critical to Metro Manila. We should take advantage of the window that we now have," he said.

As of 4 p.m. Thursday, Pagasa reported that the newest typhoon was 440 kilometers east of Catarman, Northern Samar, moving west-northwest at 24 kilometers per hour.

Pepeng has maximum sustained winds of 195 kph.

By Friday afternoon, Pepeng is expected to be 100 kms Northeast of Virac, Catanduanes or at 300 kms Southeast of Baler, Aurora.

Pagasa reported that the rest of Luzon and Visayas would experience cloudy skies and scattered rain showers within the next 24 hours.

Luzon and Visayas will also experience moderate to strong winds from the northeast to northwest.

Pagasa added that thunderstorms would become widespread over the eastern section of the country.

Rains could trigger flashfloods and landslides in the Bicol region.

Mindanao will have mostly cloudy skies with scattered rain showers and thunderstorms.

Coastal waters throughout the country could be moderate to rough.

While Pepeng is likely to bring less than half the rains of Saturday's tropical storm Ketsana (Philippine codename: Ondoy), it was expected to compound flooding in Manila, parts of which remain submerged due to blocked drainage systems.

Ketsana dumped the heaviest rains in four decades on Manila and in surrounding areas on Luzon Island, triggering floods that swamped the national capital with up to six meters (20 feet) of water.

Ketsana has left 277 dead so far in the Philippines, according to the government, and killed about 100 more after pounding Vietnam and Cambodia.

The number of people known to have been affected by Ketsana in the Philippines rose to 2.5 million on Thursday, the government said in its latest update, up nearly 300,000 from Wednesday's estimate.

The number of flood survivors staying in gymnasiums, schools and other makeshift evacuation camps also continued to balloon, with about 687,000 people staying in them, the government said.

Those in the cramped, under-resourced evacuation centers were told to prepare for the new storm, with fresh rains certain to aggravate already squalid conditions.

As Pepeng approached, worried Manila residents who had returned to their homes after the floodwaters receded, and those whose houses were unaffected, were stocking up on food and emergency lights.

Waitress Angel Francisco, 16, rushed back to check on her mother at their still-flooded home in suburban Pasig city.

?There's a new typhoon according to the news and I am worried for my mother,? she told Agence France-Presse, as she hitched a ride with a delivery truck to try and evacuate her mother.

Coast guard chief Admiral Wilfredo Tamayo said he had put his men on alert ahead of the typhoon.