Torrential rain caused by the seasonal southwest monsoon and Typhoon Saola have led to widespread flooding in parts of the Philippine capital Manila, forcing tens of thousands of people to take shelter in community buildings.

Schools, offices and stock exchanges have been closed across the capital, and authorities have issued a red alert throughout the metropolitan area, known as Metro Manila, as heavy rains are expected to continue for the next 24 hours.

The city received between 16 and 40 millimetres (0.6 to 1 inch) of rainfall per hour on the morning of 6 August, causing rivers and dams to overflow.

"If we put it in a percentage, at least 50% of Metro Manila is flooded," Jean Navarez, an official from the state weather service, told AFP.

"There will be heavy rainfall for the next 24 hours. The floods will increase," Navarez added.

Power and water supply have been affected in parts of the capital and several roads remain impassable.

Government agencies are actively engaged in rescue efforts, with rubber boats and military trucks being used as part of the operation. Residents in the shanty towns and slums are the worst affected.

"As of now, it's difficult to rescue the trapped residents, as we are battling strong currents with our life crafts," Eric Baran, an officer involved in the rescue operation, told Reuters.

Flooding was reported in the cities of Marikina, Las Pinas and Paranaque, and in areas such as Caloocan, Malabon and Navotas.

Up to 53 people died after Typhoon Saola hit the northern parts of the country on 29 July.

The flooding is the worst experienced in Manila since Typhoon Ketsana caused widespread devastation in 2009, killing over 400 people.

Reuters has released a series of pictures showing the full scale of the devastation in the Philippines.