Prime Minister Nawaz Sharif, following a nearly two-hour-long appearance before the Panama Papers joint investigation team (JIT) in Islamabad on Thursday, said his financial documents have been submitted to investigators probing his family's alleged corruption.

The premier, addressing reporters outside the Federal Judicial Academy (FJA) in the capital, said, "My financial documents are already available with all relevant institutions including the Supreme Court. Today, however, I submitted them to the JIT as well."

"It should be noted that these allegations have nothing to do with my tenure as prime minister and are not charges of corruption. They are charges against me and my family on a personal level," PM Nawaz claimed.

"I was the CM Punjab and have now been the PM for the third time. But not a single allegation of financial corruption could be brought against me," he added.

"I have put myself and my family up for trial and provided the details of financial transactions made even before my own birth," the prime minister said.

He added: "My opponents have levied charges of corruption against me. However, neither in the past, nor in the present, have any charges of corruption been proved against me and my family."

"In a few days even the JIT report will come forth along with the court's decision," he said.

"However, people should not forget that there will also be a larger JIT next year comprising 200 million people and they will decide who has worked for the betterment of the country," the premier said in an apparent warning to his opponents about the upcoming 2018 General Election.

"We will not let our opponents turn back the wheel of progress, and the nation will support us even more than it did in 2013," he asserted.

"I came here today because we are all equally accountable to the institutions," he said, adding that there is a lot more he would like to say but he would do so over the next few days.

The prime minister arrived at the JIT secretariat amid tight security and an extensive protocol around 11:15am. He appeared comfortable and relaxed upon arrival and waved at party workers, responding to their slogans and chants before entering the building.

He was accompanied by his brother Shahbaz Sharif and one of his sons.

The number of PML-N workers and lawyers supporting the PM kept swelling near the JIT secretariat in spite of the premier's earlier directive to party leaders and supporters to not converge at the venue.

Finance Minister Ishaq Dar and Defence Minister Khawaja Asif were barred from entering the FJA premises by police officials, DawnNews reported. As soon as the top government officials reached the road outside the JIT secretariat, they were informed by police that they could not go inside.

The prime minister's personal secretary was the only one allowed to enter the FJA building with him, according to DawnNews. However, the premier faced the JIT panel alone.

The JIT had prepared a questionnaire for the prime minister and his children last month. It questioned Hussain Nawaz, the PM’s elder son, on May 28. Hussain has made five appearances before the JIT so far. The investigation team has also grilled the PM's younger son, Hassan.

According to the notice issued to the PM, he was called as a witness, not as an accused party in the case.

The JIT has also summoned Punjab Chief Minister Shahbaz Sharif in connection with the probe, while Sheikh Hamad bin Jassim bin Jaber Al-Thani, the author of the Qatari letter, has reportedly offered investigators the opportunity to come to Qatar to record his statement.

The son-in-law of the prime minister retired Captain Mohammad Safdar has also been summoned by the JIT on June 25.

Security tightened for PM's appearance

Banners popped up in the capital welcoming the premier in the run-up to his JIT appearance.

All roads leading to the H-8/4 sector, which houses the Judicial Academy, will remain sealed for the duration of the prime minister's appearance and no civilians will be allowed to enter the area all day.

About 2,500 police personnel along with paramilitary troops have been deployed in and around the area. Well-equipped police teams are manning the checkpoints and the road blockades.

The sub-sector has been searched and scanned while contingents of the anti-riot unit, anti-terrorism squad and police commandos will also be deployed in and around the area. The police reserves have been put on a standby.

Journalists and media representatives have been designated a special entrance and an enclosure at the FJA, with strict orders to not break the security parameter.

The JIT saga

The Supreme Court has given the JIT two months to investigate the Sharif family and then deliver its findings.

The six-man probe team, made up of members of civilian investigative agencies and military intelligence officers, are examining three generations of the Sharif family's wealth.

The team has accused government departments of tampering with old records, but Finance Minister Ishaq Dar on Wednesday rejected such allegations, adding that the team's claims meant the process was becoming "suspicious".

The Sharif camp has sought to remove two members of the investigation team and the PML-N has voiced outrage over a leaked photograph taken from security camera footage showing Sharif's son, Hussain, appearing before the JIT.

Opinion polls suggest the PML-N is likely to win the next General Election.

A senior PML-N official told Reuters the party was unlikely to call an early election if PM Nawaz was ousted by a Supreme Court ruling, and would select a new prime minister to take over until the 2018 election.

With additional reporting from Nadir Guramani.