A cold snap which saw temperatures drop on Thursday to their lowest point in Bangladesh's post-independence history has killed around 80 people, officials said.

The weather office said the lowest temperature was recorded at three degrees Celsius (37.4 Fahrenheit) in the northern town of Syedpur and the Red Crescent said hospitals were packed with patients suffering respiratory illness.

Shah Alam, deputy head of the weather office, said the last time the temperature had dropped below three degrees Celsius was in February 1968 when Bangladesh was still part of Pakistan.

"The temperature is the lowest in Bangladesh's history," he told AFP.

The Red Crescent Society said impoverished rural areas had been worst hit as many people could not afford warm clothing or heating.

"They are not prepared for such extreme weather. Many could not even go to work," the society's general-secretary Abu Bakar said.

"According to the reports of our district offices and local administrations about 80 people have died due to cold-related diseases such as respiratory problems, pneumonia and cough," Bakar added.

Bangladesh, which is a tropical country, normally sees temperatures fall to around 10 degrees Celsius at this time of year.

The weather office said temperature were expected to rise from Saturday.