The allegations focus on Sharif's previous two terms in office in the 1990s, with opposition politician Imran Khan and others alleging the prime minister and his family illegally profited from his position.

Security was tight around the capital Islamabad on Thursday morning with the verdict due to be announced by a five-member bench of the court at 2pm local time (09:00 GMT).

In 2016, the International Consortium of Investigative Journalists (ICIJ) leaked 11.5 million documents from law firm Mossack Fonseca. Included in those documents were letters showing that three of Sharif's children - Maryam, Hassan and Hussain - were listed as beneficiaries for three companies registered in the British Virgin Islands.

The documents showed these companies were involved in a 2007 loan of $13.8 million, made using high-value Sharif-owned properties in the United Kingdom as collateral, and a separate 2007 transaction amounting to $11.2 million.

Owning off-shore companies is not illegal in Pakistan, but Sharif's political opponents allege that this $25 million was gained through corruption during his previous two terms in office as prime minister in the 1990s.

Sharif contends the money is in his children's names and that he was therefore not obliged to declare the assets on tax and other disclosure documents. Moreover, he claims it was raised through legitimate business deals, mostly based in the Gulf countries.

Late last year, the Supreme Court took up the case, after months of wrangling between the government and opposition over the formation of a commission to probe the allegations.

Now, the court will decide on whether Sharif has convinced it on the legitimate source of the funds, and indeed on whether he is liable for his children's assets. If it decides he has committed wrongdoing by not declaring the assets, it could disqualify him from his position as leader of Pakistan's government.

His daughter, Maryam, a prominent leader of Sharif's ruling PML-N party, could also face possible disqualification from holding public office in the future.

Ahead of the verdict, Maryam Sharif struck a confident tone, tweeting "Not for once have I seen my father or any member of the family anxious or concerned."

The case against the Sharifs was moved by Khan, along with political allies Jamaat-e-Islami chief Siraj-ul-Haq and Awami Muslim League chief Shaikh Rasheed Ahmed.

"We pray that as a result of this verdict Pakistan becomes a nation free of corruption," Haq told reporters on his way into the courthouse on Thursday morning.

News24