Pakistan’s supreme court has begun hearings that will decide the future of the prime minister, Nawaz Sharif, who is fighting for his job and contesting a damning corruption report by an investigative panel.

The supreme court is expected to order Sharif be tried Sharif on corruption charges, or disqualify him, but few expect the judges to dismiss the case after the panel tabled a damaging 254-page report into his family wealth.

Sharif has denied any wrongdoing after the report alleged his family’s vast wealth was beyond their means and accused his children, including presumed heir Maryam, of signing forged documents to obscure ownership of four flats in London’s Mayfair.

Sharif, 67, has rejected demands by opposition parties to resign, warning his replacement would destabilise the country and imperil hard-won economic gains since his poll victory in 2013.

“It hurts that despite all of our hard work, attempts are afoot once again to push the country back,” Sharif told a meeting of his ruling Pakistan Muslim League-Nawaz (PML-N) party at the weekend.

In April Sharif narrowly escaped disqualification after the supreme court ruled there was insufficient evidence to remove him – by a 2-3 split – over documents released by the Panama Papers leak into offshore wealth.

But it ordered further investigations, and the formation of the joint investigation team (JIT) panel.

Sharif has talked of a conspiracy against him, but has not named anyone. His allies, however, privately claim that elements of Pakistan’s powerful military and the judiciary are bent on toppling him.

The army spokesman brushed aside questions about claims the military’s hidden hand was the driving force behind the JIT investigation, saying “the Pakistan army is not directly connected”.

The six-person JIT panel included one member from the military intelligence agency and another from the Inter-Services Intelligence directorate, the country’s top spy agency.

Sharif, the son of an industrialist, is serving his third term in power and has had a fractious relationship with the army.

He was originally nurtured by the military as a civilian politician who would protect their interests, and he served as prime minister twice in the 1990s.

But relations soured and his second stint as prime minister ended when he was ousted in a 1999 coup leading to a decade of exile. Relations with the military during the current term have also been tense.

Sharif’s legal team and the opposition will be given a chance to contest the JIT findings and Sharif is also expected to be summoned to appear before the court in coming days or weeks.

Opposition politicians say Sharif is concocting claims of conspiracy to save his skin and argue that if he really wanted to protect democracy he should step down.

Imran Khan, the opposition leader who pushed the hardest for Sharif to be investigated, said the prime minister would end up in jail, and vowed protests if he was not ousted by the court.

“Either we will celebrate in Islamabad or otherwise we will hit the streets to save our democracy and to make sure we send this mafia to Adiyala jail,” Khan told supporters.