ISLAMABAD - FORMER Pakistani premier Nawaz Sharif has threatened to quit the ruling coalition if it fails to reinstate judges sacked by president Pervez Musharraf, who resigned earlier this week.

The leaders of the fragile coalition that won elections in February, headed by the party of slain ex-prime minister Benazir Bhutto, are due to meet on Friday for crucial talks on the issue.

'If the judges are not restored we will perhaps be forced to sit in the opposition,' Mr Sharif said in an interview published in the Wall Street Journal on Thursday.

'We will not try to bring the government down. But of course then we have no choice but to sit in the opposition.'

Mr Musharraf stepped down on Monday in the face of coalition threats to impeach him over constitutional violations, including his ousting of dozens of senior judges in order to push through his re-election in November.

Mr Sharif and Asif Ali Zardari, Bhutto's widower, agreed in May to reinstate nearly 60 high court and supreme court judges including chief justice Iftikhar Muhammad Chaudhry, but have since squabbled over the issue.

Mr Sharif - who was ousted from power by Mr Musharraf in 1999 - said that Mr Zardari had talked about restoring judges but not the independent-minded Chaudhry - something Bhutto's Pakistan People's Party has denied.

'He has been saying to me 'reinstating the judges minus one.' The one being the chief justice. We've said it's not a question of any individual. It's a question of the institution', Mr Sharif said.

Mr Musharraf suspended Mr Chaudhry on misconduct charges in March 2007, sparking massive nationwide protests.

The supreme court restored Mr Chaudhry in July, but Mr Musharraf imposed a state of emergency and sacked him in November when it looked like the court would overturn Mr Musharraf's re-election by the outgoing parliament.

Mr Sharif said Mr Zardari had assured him that the judges would be restored within 24 hours of removing Mr Musharraf.

'If they are not restored, it will be a bad day for democracy. It means whatever the dictator did to our country we aren't rectifying that,' Mr Sharif said.

Education minister Ahsan Iqbal, a key member of Mr Sharif's Pakistan Muslim League-N, urged Mr Zardari to honour the commitments made in an 'iron-clad' agreement which has not been made public yet.

'We are very keen to make the coalition work, but it cannot work effectively when there is lack of trust and commitments are not honoured,' Mr Iqbal said.

Mr Iqbal said that the PPP had to take a decision by Friday 'If this agreement is not fulfilled, then how can we justify our stay in the coalition?'

Mr Sharif pulled his ministers from the cabinet in May when the coalition failed for a second time to meet a deadline to reinstate the judges. Four ministers returned after the agreement to impeach Mr Musharraf. -- AFP