Former prime minister Nawaz Sharif left Pakistan on Tuesday in an air ambulance to receive medical treatment in London, his party said on Tuesday

Pakistan will allow Nawaz Sharif to leave the country for medical treatment, its foreign minister told Reuters in an interview on Thursday.

Pakistani opposition leader Shehbaz Sharif was ordered jailed on Saturday for 10 days after being arrested in a corruption case, his lawyer said, meaning he will not be able to campaign for his party ahead of crucial by-elections next week.

Pakistani authorities released former Prime Minister Nawaz Sharif and his daughter from jail on Wednesday after a court suspended prison sentences they got in July over the purchase of upscale apartments in London.

Sharif was shifted to Pakistan Institute of Medical Sciences (PIMS) in Islamabad two days ago after he reportedly fell sick inside prison.

Nawaz Sharif and his daughter Maryam Nawaz have been held at a high-security prison in Rawalpindi since July 13 following their conviction on corruption charges.

Pakistani cricket legend Imran Khan declared victory on Thursday in the general election, and said he was ready to lead the nuclear-armed nation despite a long delay in ballot counting and allegations of vote-rigging from his main opponents.

Nawaz Sharif was convicted in his absence overseas on corruption charges and arrested upon his return to Pakistan earlier his month, ahead of elections on Wednesday.

Hanif Abbasi is seen as a strong candidate for the Pakistan Muslim League Nawaz (PML-N) in Wednesday's election.

Pakistani authorities on Sunday arrested the son-in-law of ousted Prime Minister Nawaz Sharif, who was on Friday sentenced in absentia to 10 years in prison over a corruption ruling linked to his family's purchase of luxury flats in London.

The three-time former prime minister and his daughter are currently in London.

The anti-graft court ruled that the Sharif family bought properties in London with the money plundered from Pakistan in the 1990s.