Islamabad: Pakistan's jailed former prime minister Nawaz Sharif has accused the federal government of deliberately impeding his treatment for heart-related ailments, according to a media report.

Sharif's brother and PML-N President Shehbaz Sharif said the three-time former prime minister is in "high spirits" but still requires immediate medical treatment.

He (Sharif) says the doctors who examined him earlier said they were only sent to check and verify his health condition. The doctors said they did not have any orders to start his treatment, Shehbaz was quoted as saying by the Express Tribune.

The National Assembly opposition leader said the government's failure to address concerns regarding Sharif's health was regrettable.

"It is sad to see that the medical treatment of a three-time former prime minister has been made a political issue. This victimisation must end, he said.

Shehbaz's statements come a day after the Punjab government wrote a letter to the former prime minister stating that he was free to pursue treatment at a hospital of his choosing in Lahore.

Sharif on Wednesday refused to be relocated to a hospital for treatment despite requests by his family members, saying he prefers an "honourable death" over kneeling to "politics being done" by the government in the name of his treatment.

Sharif, 69, is serving a seven-year imprisonment in the Al-Azizia Steel Mills corruption case at the Kot Lakhpat Jail since December 2018.

The Pakistan Muslim League-Nawaz (PML-N) supremo has suffered four angina attacks last week, his daughter Maryam Nawaz said on Tuesday.

The Sharif family is complaining that the government is not providing health facilities to the former premier who has serious health complications.