Afghan President Ashraf Ghani on Sunday took to Twitter to wish Prime Minister Nawaz Sharif well for his upcoming open-heart surgery.

"I would like to send my best wishes to PM Nawaz Sharif and his family. Hope the surgery goes alright. We pray for his speedy recuperation," he said.

Indian Prime Minister Narendra Modi also conveyed well wishes to Nawaz on Saturday.

"My best wishes to PM Nawaz Sharif Sahab for his open heart surgery on Tuesday. And for his speedy recovery & good health," Modi tweeted, tagging Nawaz's daughter, Maryam, in his post.

PM Nawaz is scheduled to undergo an open-heart surgery in a UK hospital on Tuesday. He will be overseeing the affairs of his government from London.

A senior government official said, “It may take a little over a week for the prime minister to recover and travel back to Pakistan.”

The premier is in constant contact with his ministers with no postponements or delays in matters pertaining to the routine functioning of the state, said a statement issued by the PM Office in Islamabad.

Meanwhile, former chief justice Iftikhar Muhammad Chaudhry feared that in the PM’s absence the upcoming budget session would be entirely unconstitutional and illegal.

He suggested that the only remedy left to provide legal cover to the passage of budget and avoid a constitutional and financial crisis was an in-house change with the PM stepping down to pave the way for his successor in the shape of a new leader of the house.

Special assistant and spokesman for the prime minister, Musadik Malik, told the electronic media on Friday night that all affairs of the state would continue as per the law of the land and Mr Dar would be responsible for managing the routine matters of the government.