Sharif, who in the past has undergone heart surgery, visited consultants on Harley Street on Tuesday and Wednesday and is scheduled for more scans on Thursday, according to the report.
National Accountability Bureau alleged that RehmanMir Shakilur Rehman was given 54 plots of land in Lahore's Jauhar Town phase-II by then Punjab CM Sharif in 1986 in violation of the relevant laws.
Nawaz Sharif attacks Pakistan Army, ISI chief as Opposition says 'sun about to set' on Imran Khan govt
The Pakistan Democratic Movement (PDM), a coalition of 11 Opposition parties, was formed to oust Khan from power on September 20.
For over nearly a month, the Pakistan government has made several attempts to get Sharif's arrest warrant signed
His daughter Maryam was sentenced to seven years in prison for abetment and his son-in-law Captain (retd) Mohammad Safdar to one year.
Sharif had submitted an undertaking to the court that he would return within four weeks or as soon as he was declared healthy and fit to travel by doctors.
Pakistan's Opposition parties have alleged that paramilitary Frontier Corps reportedly pressurised Sindh Police to arrest Safdar.
Maryam's husband Capt (retd) Mohammad Safdar was earlier arrested in Karachi for allegedly violating the sanctity of Quaid-e-Azam mausoleum.
Shehbaz termed unholy alliance of Imran Khan and NAB behind political victimisation of opposition leaders.
He argued that since 70-year-old Sharif is in England, the proclamation may be published in The Guardian and Daily Telegraph.
The arrest comes after a first information report was registered against Maryam, Safdar and 200 others for violating the sanctity of the Quaid's mausoleum.
So far no official announcement has been made regarding the arrest by the police.
Khan said Sharif opted to use negative language against the army leadership at a time when soldiers were sacrificing their lives for the nation.
The PML-Nawaz chief alleged that army chief Gen Qamar Javed Bajwa is directly responsible for the miseries and sufferings of the people by imposing an inept PTI government.
The Registrar of the Islamabad High Court (IHC) on Friday issued a written order about the proceedings on the appeal by Sharif in Al-Azizia and Avenfield graft cases, the Dawn News reported.