A Pakistani court has sentenced ousted prime minister Nawaz Sharif to 10 years in prison over his family's purchase of several luxurious London properties, in a major blow to his party ahead of a general election in July.

Sharif, 68, was ousted from power in July last year by the country's supreme court over corruption allegations connected to the Panama Papers scandal.

The guilty verdict in absentia threatens to end the career of one Pakistan's most high-profile politicians over the last four decades, a political survivor who served as prime minister on three occasions.

Sharif's daughter Maryam, widely seen as his chosen political heir, was also sentenced to seven years in prison. Her politician husband Muhammad Safdar was sentenced to one year in prison, prosecution lawyer Sardar Muzaffar Abbasi said.

Mr Abbasi added that the anti-corruption court ordered Sharif to pay a fine of 8 million pounds ($14.3 million) and Maryam was fined 2 million pounds ($ 3.6 million), while ordering the confiscation of the London properties on behalf of the Pakistani government.

Both Sharif and his daughter were in London on Friday with Sharif's wife, Kulsoom, who is being treated there for cancer and is in a coma after suffering a heart attack last month.

They both denied wrongdoing and are expected to appeal.

Sharif says claims are politically motivated

Supporters of Sharif react outside the court following the ruling against him. ( AP: B.K. Bangash )

The National Accountability Bureau (NAB) court accused Sharif and his family of being unable to legitimately show the money trail for the purchase of several London flats, mostly in the mid-1990s.

Sharif was ousted by the Supreme Court in July 2017 and barred from politics for being "dishonest" by failing to report a monthly income of 10,000 Emirati dirham ($3,674) from a company owned by his son. He denies drawing the monthly salary.

But he has kept control of the Pakistan Muslim League-Nawaz (PML-N) party that he founded.

Sharif had denounced the court proceedings against him as politically motivated and a judicial witch-hunt, often suggesting the hidden hand of the military was to blame.

Hours before the verdict, Maryam's husband Safdar referred to it as a "funeral" for justice, the PML-N media office said in a statement.

"It is to be seen if this decision is written by a judge or a general," Mr Safdar said.

The military, which has ruled the nuclear-armed country for almost half of its history, denies involvement in civilian politics.

But the military ended Sharif's second stint in power in 1999 in a bloodless coup.

The decision against the Sharifs comes at a time of intensifying suspicion of military meddling in politics ahead of the July 25 polls, as well as media complaints that the press is being muzzled.

Sharif alleged the charges were made against him to tip the scales in favour of cricketer-turned-politician Imran Khan (pictured) in the run-up to the election. ( AP: B.K. Bangash )

Sharif has argued that the military, in cahoots with top members of the judiciary, has used a series of cases against him and others in his party to tip the scales in favour of cricketer-turned-politician Imran Khan in the run-up to the election.

Mr Khan is running on a socially conservative, anti-corruption platform. He denies colluding with the military establishment and praises the disqualifications and prosecutions of PML-N figures as a long-needed crackdown on graft.

Reuters