A glacial lake in a mountainous region in northern Pakistan has burst, triggering a massive flood that swept away a bridge.

The phenomenon, known as a glacial lake outburst flood, occurred on Saturday at Hunza Valley at the foot of the Karakoram mountain range.

Footage taken at the scene show a muddy torrent washing away a concrete bridge beam, causing half of the bridge to collapse.

Local media report that no one was injured in the disaster.

Pakistan has been hit by a heatwave, with a daytime high of 49 degrees Celsius being observed in late April in the southern city of Jacobabad.

In the past 20 days, there was a 40 percent rise in water levels at the glacier lake that unleashed the flood.

Local media say the heatwave has caused more than 3,000 glacial lakes to form, of which 33 could burst.

Pakistani Foreign Minister Bilawal Bhutto Zardari noted in a statement on Saturday that concerted efforts are needed on the issue of climate change.