ISLAMABAD, Pakistan -- At least 77 people have died in monsoon rains lashing Pakistan, the country's climate change minister said Wednesday, warning more heavier-than-usual downpours lay ahead.

"For me, it's a national tragedy," Sherry Rehman told a news conference in the capital, adding the toll was taken from June 14, when the monsoon started.

"When people die like that, it's not a small thing... It is just the beginning. We have to prepare for it."

Most of the deaths were in the southwestern province of Balochistan, where 39 people drowned or were electrocuted by downed power lines.

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

Poorly built homes across Pakistan -- particularly in rural areas -- are prone to collapse in floods, which also destroy huge tracts of prime farmland.

The worst floods of recent times were in 2010 -- covering almost a fifth of the country's landmass -- killing nearly 2,000 people and displacing 20 million.

Pakistan is the eighth most vulnerable country to extreme weather caused by climate change, according to the Global Climate Risk Index compiled by environmental NGO Germanwatch.

"One day you have drought and next morning you are expecting flash flood... so you can see how serious the situation is in Pakistan", Rehman said.