Pictures: Pakistan city of Karachi paralysed by monsoon rain

People wade through a flooded road after heavy rains, in Karachi. Officials say monsoon rains lashed Pakistan's largest city of Karachi and elsewhere, inundating several low-lying neighbourhoods, flooding even the city's upscale areas and disrupting normal life.

A man pushes his motorbike through a flooded street in Karachi. Since June 14, more than 300 people have been killed in rain-related incidents across Pakistan since rains started lashing the nation last month.

Girls use a temporary raft across a flooded street in a residential area in Karachi. A weather emergency was declared in Karachi as heavier-than-usual monsoon rains continue to lash the city, flooding homes and making streets impassable.

A boy uses bamboo raft across a flooded street in Karachi. This year's monsoon is being felt hardest in cities, where poor infrastructure and services lead to clogged drains and culverts - and the collapse of the sewage system. The result is widespread flooding, particularly in low-lying areas, and usually in poor neighbourhoods.

A boy wades through his flooded house in Karachi. An "unprecedented" 568 millimetres of rain has fallen in the city this month - nearly triple Karachi's recent averages and more than four times that of two decades ago, says Sardar Sarfaraz, director of the Pakistan Meteorological Department.

Environmentalist Arif Zubair conceded monsoons can regularly cause natural havoc, but is clear what is to blame for the worsening situation - climate change.

People wade across a flooded street after heavy monsoon rainfall in Karachi. Though several key roads were cleared by the administration after hours-long efforts in the cities, life remained miserable in several low-lying areas, residential neighbourhoods, housing societies and commercial centres which remained flooded.

Edhi volunteers bring a boat to evacuate stranded people along a flooded street in Karachi.

The monsoon, which usually lasts from June to September, is essential for irrigating crops and replenishing lakes and dams across the subcontinent, but also brings a wave of destruction each year.

Due to the heavy downpour, Monday had already been declared a holiday for the citizens of Karachi and Hyderabad.

Vehicles drive during a heavy rainfall, in Rawalpindi. The Pakistan Meteorological Department forecast more rains in the coming days, saying the monsoon spell would remain active during the ongoing week.

Troops use a water pump to remove water from a flooded residential area in Karachi.

The weather office has advised all concerned authorities to remain alert as heavy rainfall may generate urban flooding and waterlogging in several cities across the country, and may trigger landslides in northern areas of Pakistan.

A fruit vendor pushes his cart across a flooded street following heavy monsoon rains in Karachi.

A resident uses a bucket to remove water from his flooded house in Karachi.

Motorcyclists navigate a flooded road after heavy rains, in Karachi.

Motorcyclists cross a flooded street in Karachi.