Karzai arrived here on Sunday along with an Afghan delegation to represent his country in the meeting.
The spokesperson further said that representatives from other 12 participating countries, 16 supporting countries and 12 regional and international organisations have been invited to attend the meeting.
The Heart of Asia-Istanbul Process was launched in 2011 to bring together regional countries to promote peace and prosperity in Afghanistan through concerted efforts of participating and supporting countries as well as international and regional organisations engaged in the process.
The Process is also aimed at providing a platform to discuss regional issues, particularly encouraging security, political, and economic co-operation among Afghanistan and its neighbours.
It also aimed at expanding co-ordination between Afghanistan and its neighbours and regional partners in facing common threats, including counterterrorism, counter narcotics, poverty, and extremism, including through a set of six Confidence Building Measures.
Pakistan is the co-chair for 2015 with Afghanistan (permanent co-chair). It will host the fifth Ministerial Conference at Islamabad later this year.
"As the co-chair, Pakistan will take initiatives to take the Process forward from the Beijing Conference held in October 2014", Khalilullah said, adding it will play a lead role in various activities of the process, including three senior officials meetings to discuss topics pertaining to the theme of this year's Ministerial Conference ie. Heart of Asia-Istanbul Process: Enhanced Co-operation for Countering Security Threats and Promoting Economic Connectivity.
He said that the deliberations in these senior officials meetings would form the basis for the Islamabad Declaration, to be endorsed by Heart of Asia countries and organisations during the Ministerial Conference.
Last month, Foreign Secretary hosted the representatives of the member and supporting countries and regional and international organisations of the Heart of Asia-Istanbul Process, in which he highlighted the importance Pakistan attached to the common principles and commitments guiding the Istanbul process.
He encouraged the member and supporting countries and organisations to synergize their efforts to pilot Afghanistan and the Heart of Asia region towards stability and prosperity, adding enhanced regional co-operation is crucial to reinforcing Afghanistan's national efforts for economic development and deeper regional integration.