The court trying deposed Pakistani premier Nawaz Sharif has heard that he tried to stop a plane carrying army chief General Pervez Musharraf from landing before the general launched a military coup.

Key prosecution witness Aminullah Chaudhry, the former director-general of Pakistan's civil aviation, was giving evidence on the second day of the trial of Nawaz Sharif and six others on charges of attempted murder, abduction and hijacking.

Three of the charges carry either the death penalty or life imprisonment.

Defence lawyers at the trial have continued to cross-examine Mr Chaudhry about the exact nature of the instructions from Nawaz Sharif.

Key witness

Aminullah Chaudhry's testimony relates to the sequence of events on 12 October, the day General Musharraf overthrew Mr Sharif in a bloodless coup.

The general was returning to Pakistan on a commercial flight carrying 200 passengers, when his flight was refused permission to land.

The plane did in fact eventually land in Karachi, but the prosecution says that was only because the military launched a coup.

"PM Nawaz Sharif came on the line. He instructed me to obtain the details of the flight and ensure that the flight should not land in any airport in Pakistan," Mr Chaudhry told the court.

Asked about the timing of his conversation, Mr Chaudhry said that it was "a few minutes before 7 pm (local time)."

He said the army did not seize the Karachi air traffic control tower until 7.15 pm.

"Yes, when the army took over the air traffic control tower the government of Nawaz Sharif was in power," he said.

Cross examination

However, he conceded to defence lawyers that the ousted prime minister's instructions only dealt with not allowing the plane to land in Pakistan..

Other orders about closing Karachi airport and diverting the plane were a consequence of those instructions.

Originally accused along with Nawaz Sharif, Mr Chaudhry agreed to give evidence against the former premier in return for a pardon.

Correspondents say Mr Chaudhry's evidence goes to the heart of the case against Mr Sharif.

The court also heard from the officer in charge of operations at Karachi airport, Syed Yusuf Abbas.

Not enough fuel

He said the pilot told the control tower he did not have enough fuel to fly to another country, and wanted to land at the alternative domestic airport to Karachi, Nawabshah.

But directions were given that he should fly to another country at his own risk - this was then changed after he said he had only 45 minutes of fuel left.

He finally landed at Karachi after the army took control of the airport.

The military government has alleged that the plane landed with only a few minutes' worth of fuel left.

The trial, which started on Wednesday after a series of delays, is expected to last for several weeks.