Former prime minister Nawaz Sharif left for London on Tuesday, 20 days after he was released on bail from a seven-year sentence for corruption.

The PML-N supremo, who has been diagnosed with an immune system disorder, was accompanied by his brother Shehbaz Sharif and his personal physician Dr Adnan Khan. They reached the UK capital after 10pm PST.

“Nawaz Sharif will go to Boston after going through a detailed checkup in London. During his travel, he will stay in Doha for two hours,” PML-N leader Pervaiz Rashid told Reuters.

The air ambulance arrived from Doha early morning at Lahore airport's Haj Terminal. An intensive care unit and an operation theatre had been set up inside while a team of doctors and paramedics were also on board.

According to immigration sources, Nawaz's medical files were handed over to the team traveling with the former prime minister in the air ambulance. Doctors also conducted blood tests prior to the departure.

PML-N spokesperson Marriyum Aurangzeb said that Nawaz's plane would stop in Qatar for a refuel. She said the medical team would also be changed.

The 69-year-old PML-N supremo, who has bail in two corruption cases and is facing another reference by the National Accountability Bureau, was accompanied to the airport by a large number of supporters as well as party leaders. Party leaders, including Khawaja Asif and Ahsan Iqbal, were also present to see off the leader.

The former premier's mother, other family members and his daughter Maryam — who surrendered her passport to secure her release in the Chaudhry Sugar Mills case earlier this month — bid farewell to him at the house. A large number of supporters and workers had gathered outside Jati Umra since the morning prior to Nawaz's departure.

In a separate statement issued earlier on Tuesday, Aurangzeb said that doctors completed a medical examination of Nawaz ahead of his departure and he was administered high doses of steroids and medicines to ensure that his condition remains stable during travel.

His departure comes a day after the interior ministry issued a notification, allowing the former prime minister to travel abroad for medical treatment, saying that the decision was an "interim arrangement" in light of the LHC's order, which was passed last week.

In its notification, the ministry reproduced the undertakings provided by Shehbaz Sharif and Nawaz to the LHC in which the terms of their travel and return have been laid out. The former prime minister's name remains on the Exit Control List (ECL).

'Praying for Nawaz's recovery'

Soon after Nawaz left, Prime Minister Imran Khan's aide Firdous Ashiq Awan wished Nawaz a "speedy recovery so that he can return and face [the courts]".

In a tweet, she said: "[We are] praying that God grants a complete recovery to Nawaz Sharif. We are praying for his health and [for his] speedy recovery so that he can return and face the law. With his conduct, Prime Minister Imran Khan has set a golden example of respect for humanity and supremacy of law."

Minister for Science and Technology Fawad Chaudhry also reacted to Nawaz's departure and said that the "journey from 'why was I expelled' to 'expel me for God's sake' is now approaching its end".

"When such leadership demands respect for vote, it actually insults the democratic process," he said in a tweet. "I sympathise with those workers of the PML-N who consider Nawaz Sharif their leader and tire themselves day and night."

Later, in a press conference in Islamabad, Chaudhry said that the government was praying for Nawaz's health. He added that the "impression that an NRO had been granted should not be there".

LHC order

After much deliberation and meetings, the government had agreed to allow Nawaz to travel abroad, with the condition that indemnity bonds amounting to Rs7-7.5 billion be furnished. The PML-N had rejected the condition and had taken the matter to the LHC, which — in a blow to the Centre — ordered the federal government to remove his name from the ECL without any conditions. The verdict was issued after Nawaz signed a court-approved undertaking, saying that he would return to the country within four weeks.

Shehbaz too signed an undertaking, which stated he would "ensure return" of his brother "within four weeks or on certification by doctors that he has regained his health and is fit to return back to Pakistan". Nawaz was allowed to leave the country for a period of four weeks, extendable on the basis of medical reports.

Nawaz, who has been diagnosed with an immune system disorder, was recommended by doctors to go abroad as his condition continued to deteriorate despite treatment. He was rushed to Services hospital from the Kot Lakhpat jail — where he was serving a prison sentence granted by an accountability court that found him guilty of corruption in the Al Azizia case — after Dr Khan raised an alarm over the former prime minister's deteriorated health.

Nawaz was granted bail by the Islamabad High Court on humanitarian grounds, in the Al Azizia case earlier this month. He also obtained bail in the ongoing Chaudhry Sugar Mills case, in which he is a suspect, from the LHC.