Zardari and Ahmadinejad held one-on-one and delegation-level talks shortly after the Iranian leader arrived in Islamabad for bilateral talks and a trilateral summit with Afghanistan.
Zardari and Ahmadinejad on Thursday discussed progress on the multi-billion dollar Iran-Pakistan gas pipeline project that is aimed at helping Islamabad overcome an energy shortfall due to rapidly growing domestic and industrial needs, officials said.
They did not give details. The officials said the talks between Zardari and Ahmadinejad focussed on political and economic cooperation and measures to strengthen bilateral ties.
The two leaders initially held one-on-one talks and were later joined by their respective delegations for comprehensive talks covering all areas of cooperation, the officials said.
Pakistan has said it is committed to the early implementation of the troubled gas pipeline project with Iran. Questions have been raised about the viability of the project following sanctions imposed on Iran by Western powers over its nuclear programme.
The US has mounted pressure on Pakistan not to go ahead with the gas pipeline project. Ahmadinejad arrived in Islamabad shortly after Afghan President Hamid Karzai flew in with a high-level delegation.
Karzai held talks with Zardari and Prime Minister Yousuf Raza Gilani. The Presidents of Afghanistan, Iran and Pakistan will hold two sessions as part of their trilateral summit, on Thursday evening and Friday.