Islamabad, Pakistan (CNN)Former Pakistani Prime Minister Nawaz Sharif and his daughter have been arrested and are being held in Islamabad after they flew back from the United Kingdom to face prison sentences, authorities said.
The return to Pakistan of Sharif and his daughter, Maryam, on Friday comes one week after a court found them guilty of corruption-related charges and sentenced them to 10 and seven years in prison, respectively.
They first flew from London to Lahore, where authorities took them into custody and escorted them onto a small government plane, which took off for Islamabad, a source who was on the first plane told CNN on condition of anonymity.
In a video released early Friday morning by the Pakistan Muslim League Nawaz (PML-N) party, Sharif could be seen addressing his supporters from inside an airplane, stating that he was returning to Pakistan as a "sacrifice for the future generations of the country and for its political stability."
"The country is at a critical juncture right now. I have done what I could," he said. "I am aware that I have been sentenced to 10 years and will be taken to a jail cell straightaway."
After arriving in Islamabad, Sharif and his daughter were being held in the rest house of the Sihala Police Training College, the office of Islamabad's chief commissioner said.
Protests in the streets
Ahead of the pair's return, PMLN members and other Sharif loyalists -- who feel the Sharifs have been unfairly targeted -- entered the streets of Lahore after Friday prayers for a procession to support them.
The protests jammed traffic across the city into the evening.
Former Punjab chief minister and current PMLN party head Shahbaz Sharif -- the brother of the former Prime Minister -- announced on Thursday that he would lead the "reception rally" of party workers to welcome his sibling's return.
Supporters of Pakistan's ousted Prime Minister Nawaz Sharif and his younger brother Shahbaz Sharif gather at the venue where the younger Sharif would lead a rally.
Shahbaz Sharif, who last year inherited the leadership of PMLN, said in a statement last Friday that the party "strongly rejects" the guilty verdict.
"The decision is flawed, politically motivated and has glaring loopholes," he said.
Pakistanis are due to head to the polls on July 25, and the return of the Sharifs from the UK is being seen as an attempt by their political allies to shore up support -- particularly as candidates have been jumping ship and renouncing loyalties.
Authorities made a number of restrictive moves in anticipation of the procession. Pakistan's Interior Ministry ordered cell phone coverage switched off Friday in some parts of Lahore ahead of the arrival of the Sharifs, who had been in the UK caring for Sharif's wife, Khulsoom, who is receiving cancer treatment.
An emergency law that prevents the public assembly of more than four people also was temporarily put in place, but the procession went on.
Shipping containers were placed across major thoroughfares by the Punjab government to restrict their movements.
Caretaker Interior Minister Shaukhat Javed earlier told CNN that around 1,600 security officials would be positioned around Lahore airport and a request to bring in paramilitary troops was made in case the "law-and-order situation get(s) out of hand."
According to party spokesman Mushahid Hussain, close to 500 party workers were detained Thursday night by security forces.
Pakistani policemen carry their gear as they arrive at the Alama Iqbal International Airport ahead of the arrival Friday of Sharif from London.
Sentenced and fined
The country's National Accountability Court last Friday sentenced the former ruler to 10 years in prison and fined him £8 million ($10.5 million) relating to corruption charges over his family's purchase of overseas properties. The fine was issued in British pounds, as that is where the properties are located.
Maryam, widely seen as her father's heir apparent, was also found guilty and is facing seven years in prison and a £2 million ($2.6 million) fine. Her husband, Captain Safdar, has received a one-year jail sentence.
All three have been barred from engaging in politics for 10 years, and four properties in London will be confiscated by the Pakistani state, according to the verdict. They have 10 days to appeal the verdict at the Islamabad High Court.
Sharif speaks during a UK PMLN Party Workers Convention meeting in July with supporters in London.
The Supreme Court a year ago ordered Sharif to step down from office following a government probe into his family's wealth after publication of the Panama Papers.
His PMLN party completed its term in May, and an interim government is in power until vote this month.
