Pakistani nuclear scientist Abdul Qadeer Khan, who is the founder of Pakistani nuclear programme, passed away due to lung problems on Sunday at the age of 85, his family said.

Khan's health condition started deteriorating on Saturday night, after which he was rushed to the Khan Research Laboratories Hospital in Islamabad, according to his family members, Xinhua news agency reported.

Earlier in August, the nuclear scientist was admitted to the same hospital after testing positive for COVID-19. He had been moved back home after being successfully treated for the coronavirus disease, according to government officials.

Pakistani Prime Minister Imran Khan expressed his condolences to the family of the nuclear scientist, saying on Twitter that he was loved by the nation because of "his critical contribution in making Pakistan a nuclear weapon state".

"For the people of Pakistan he was a national icon," the prime minister said.

Pakistani President Arif Alvi said in a tweet that the nuclear scientist has helped Pakistan "develop nation-saving nuclear deterrence, and a grateful nation will never forget his services in this regard".