Pakistan Muslim League-N chief Nawaz Sharif on Monday assured ruling Pakistan People's Party co-chairman and President-elect Asif Ali Zardari that his party would cooperate with the Pakistan People's Party-led government to strengthen democracy in the country.

Sharif, who called on Zardari to congratulate him on his win in the presidential poll, ruled out returning to the ruling coalition and said the PML-N would play a 'healthy role' in the opposition.

The PML-N pulled out of the alliance last month after accusing Zardari of reneging on several promises.

Senior PML-N leader Ahsan Iqbal described the meeting as a 'courtesy call' and said the two sides had not held any detailed political discussions.

Zardari is set to be sworn in as President on Tuesday and Sharif will be unable to attend the event as he will be leaving for London [Images] to be with his wife, who is recovering after surgery.

"He (Sharif) will be away for the next five-six days, so he wanted to personally congratulate Zardari before he left the country," Iqbal told media persons.

Zardari had wanted the PML-N to return to the coalition but Sharif told him the party would play a 'healthy role in the opposition' and cooperate with the government to strengthen democracy, Iqbal said.

In the past few days, the PML-N has also called on Zardari to quit his position as party chief in the PPP so that he could function as a non-partisan President.

Sharif, his brother Punjab Chief Minister Shahbaz Sharif and senior PML-N leaders called on Zardari at the Prime Minister's House. Prime Minister Yousuf Raza Gilani [Images] and senior PPP leaders too were present.

"The purpose of this meeting was to set a new tradition in Pakistan's democracy and politics that we must accept the victory of the candidate who has won the election and the party, which has lost the election, must congratulate the winning party," Iqbal said.

The PML-N will support all the good actions of the PPP-led coalition. At the same time, it would suggest improvements wherever it noticed shortcomings, he said.

"While sitting in the opposition, the PML-N will not allow the system to be weakened. We want the transition to democracy to be completed and we want to see democracy strengthened," he added.

"I hope that both parties will continue to work together while they in government and in opposition in the spirit (laid down) in the Charter of Democracy for strengthening the democratic process in Pakistan," Iqbal said, referring to an agreement signed by Sharif and late PPP chairperson Benazir Bhutto [Images] in 2006.

In the wake of a war of words between PPP and PML-N leaders in Punjab, where the PML-N is in power, Iqbal hoped both parties would accept each other's mandate.

"Just as we have accepted with an open heart the PPP's victory and mandate in the centre, we hope that the PPP will reciprocate and open-heartedly accept our mandate in Punjab," he said.

The presidential election had 'amply proven that the PML-N government enjoys a very comfortable majority without the PPP's support in the Punjab assembly'.

The PML-N candidate bagged the most votes in the Punjab assembly while Zardari swept the poll in the three other provincial assemblies.

Some PML-N leaders would attend Zardari's swearing-in ceremony even though the party has reservations about Supreme Court Chief Justice Abdul Hamid Dogar, who will administer the oath, Iqbal said.

The PML-N does not accept Dogar as the constitutional Chief Justice as he was appointed during last year's emergency after former President Pervez Musharraf [Images] sacked dozens of judges. Iqbal reiterated the PML-N's demand for unconditional reinstatement of the deposed judges.