Anwar died at his Elephant Road residence in Dhaka at 1:25am Tuesday, BNP Senior Joint Secretary General Ruhul Kabir Rizvi told bdnews24.com.
The senior BNP leader had long been absent from party meetings due to his illness.
The retired bureaucrat-turned-politician is survived by his wife, daughter and two sons.
Family members said that he will be buried in the family graveyard at his native Comilla on Wednesday after his daughter and one of the sons return from the US.
Mirza Fakhrul went to Anwar's residence in the morning and expressed his condolences to the family.
Mohammad Khorshed Anwar, known as MK Anwar, was born in 1933 in Comilla.
He joined the then Pakistan civil service and served the Bangladesh administration after independence.
Anwar served as the finance secretary and cabinet secretary before retiring in 1990.
He then joined the BNP and was elected a lawmaker from Comilla's Homna five times.
Anwar served as the agriculture minister in the Khaleda administration between 2001 and 2006.