Nawaz Sharif is serving a seven-year jail term in a corruption case. (Reuters)

Pakistan's jailed former Prime Minister Nawaz Sharif was hospitalised on Monday night after his health deteriorated. Doctors said that his platelet count fell and he had to be hospitalised immediately.

"Former PM Nawaz Sharif is detected to have critically low Platelet Count that could be due to multiple pathologies and requires immediate in-hospital care," Nawaz Sharif's personal physician Dr Adnan Khan said in a tweet on Monday.

Dr Khan said he met Nawaz Sharif in Lahore and found him visibly unwell.

"He has multiple life-threatening health issues. The matter is of utmost urgency and he should be hospitalised," he said.

A spokesperson for Pakistan's National Accountability Bureau said Nawaz Sharif has been shifted to a hospital where he is being treated by a team of doctors. "Nawaz Sharif is likely to stay in hospital on Monday night," he said.

Nawaz Sharif's brother Shahbaz Sharif has alleged that despite his worsening health, he was not shifted to hospital earlier. He said Prime Minister Imran Khan will be responsible if anything happens to his brother.

Doctors said Nawaz Sharif required aggressive medication and "regular medical follow-ups" to avoid health complications.