Maulana Sami-ul-Haq, the head of a faction of the Jamiat Ulema-e-Islam, met Sharif at the Prime Minister's House.
"Both the leaders remained together for some time and discussed matters relating to national Importance," an official statement said without giving details.
Media reports said talks with the banned Taliban was the main issue on the agenda and Haq assured the premier that he would use his influence to ensure the peace process progresses in the right direction.
Haq heads Darul Uloom Haqqania, a madrassa where many top Taliban leaders have studied.
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Sharif has been personally meeting political and religious leaders to kick start negotiations with the militants.
The premier briefed Haq about a recent military action in Waziristan region and invited him to get personally involved in the process for talks with the Taliban, The Express Tribune reported.
Haq's party had earlier not been invited to an All-Parties Conference organised by Sharif. The party had also featured nowhere in the government's plans to initiate dialogue with the Taliban.
The government had earlier invited Haq to help facilitate peace negotiations but after hearing of Haq's, his party was removed for list of facilitators for talks.
In the 1980s, many graduates of Haq's madrassa, including Afghan Taliban chief Mullah Omar, left their books and picked up guns to fight invading Russian forces in neighbouring Afghanistan.