A Pakistani court indicted jailed former Prime Minister Imran Khan and his third wife Bushra Bibi on Tuesday on charges that they allegedly received land as a bribe by misusing his office during his premiership, his party said.

The latest charges follow a string of convictions against Khan in the months leading up to the Feb 8 national election, where his supporters won the most seats overall.

Khan, 71, has been in jail since August in connection with other cases, and has previously denied the allegations.

He had already been convicted in four cases with sentences of as much as 14 years in prison - including two on graft charges, that also disqualified him from taking part in politics for 10 years.

His trials are being held on a jail's premises on security grounds.

The couple pleaded not guilty to the indictment charges, Khan's Pakistan Tehreek-e-Insaf (PTI) party said.

Candidates backed by the PTI won the largest number of seats in parliament in the election earlier this month by defying all odds and what it says was a military backed crackdown. His supporters ran as independents instead of as a single bloc after his party was barred from the polls.

But his opposition parties led by the Sharif and Bhutto dynasties cobbled together an alliance to form a minority coalition government.

The latest indictment is related to Al-Qadir Trust, which is a non-governmental welfare organisation set up by Khan and his third wife Bushra Bibi in 2018 when he was still in office.

Prosecutors say the trust was a front for Khan to receive a valuable 60 acres (24 hectares) of land in a district outside Islamabad and another large piece of land close to Khan's hilltop mansion in the capital as a bribe from a real estate developer, Malik Riaz Hussain, who is one of Pakistan's richest and most powerful businessmen.

Hussain, who hasn't appeared before an anti-graft agency to submit his reply to summons issued to him late last year, has denied any wrongdoing.

The PTI condemned the indictment.

"Trials conducted behind prison walls (are) only meant to pave the way for miscarriage of justice," it said in a statement, terming them politically motivated cases to keep Khan behind bars.

The PTI party has rejected the election results, alleging widespread fraud.

The powerful military, which plays an outsized role in making or breaking governments in the nuclear-armed South Asian nation of 241 million people, fell out with Khan before he was ousted in a parliament vote of confidence in April 2022.

He has alleged that generals backed his ouster to bring his opponents to power, a charge the army and the opposition deny.