Bangladesh's disaster management and relief ministry on Friday announced that at least 13 people have died while 4.5 million are left stranded as a result of deadly floods, triggered by heavy rains.

The South Asian nation of 170 million people, known for its extensive river networks, has witnessed a recurring pattern of floods, making it susceptible to climate-related crises, according to the Global Climate Risk Index.

"4.5 million people have been affected, and 13 people have died across the country," AFP reported citing the disaster ministry's bulletin on Friday.

Nearly 190,000 others were taken to emergency relief shelters, according to the bulletin.

Altogether, 11 of the country's 64 districts were affected by the flooding, the bulletin added.

Feni, about 100 kilometres (60 miles) northwest of the main port city of Chittagong, was worst-hit.

"It's a catastrophic situation here," rescue volunteer Zahed Hossain Bhuiya, 35, told AFP in Feni. "We are trying to rescue as many people as we can."

According to Chief Administrative Officer of Ramu district, Rasedul Islam, three of those who died drowned in floodwaters in the southeastern region of Cox's Bazar, Al Jazeera reported.

Bangladesh faces widespread destruction from annual monsoon rains every year, but climate change has triggered the shifting of weather patterns and has caused an increase in the number of extreme weather events.

The army and the navy have been deployed, with speedboats and helicopters rescuing those stranded by the swollen rivers.