Iranian President Mahmoud Ahmadinejad and his Pakistani counterpart Asif Ali Zardari will officially inaugurate the Iran-Pakistan gas pipeline project on Monday, Press TV reported on Sunday.
The $7.5-billion project will be inaugurated at a ceremony in the border city of Chahbahar.
Iran has constructed 900 km of the 1,600-km pipeline on its soil, and both Iranian and Pakistani firms will undertake the construction of the remaining part in Pakistan.
On completion, Iran will export 21.5 million cubic metres of natural gas to Pakistan on a daily basis.
Despite strong opposition by the US, Zardari earlier said that his energy-starved country would pursue the gas pipeline project and would persuade the critics that Pakistan needs energy.
Pakistan and Iran have held a series of talks on the project for nearly two decades, but it was finalised during the recent visit to Tehran by Zardari.
Pakistani media reported that Tehran had agreed to provide a $500-million loan to Islamabad to partly finance the construction of the pipeline on the Pakistan side.
Both countries have agreed to complete the project by mid-2014.
President Zardari will be accompanied by a big delegation of ministers, members of parliament, political leaders, senior officials and journalists, officials said.
The Pakistani foreign ministry said several heads of state have been invited for the ceremony.
A foreign ministry spokesman, however, rejected the impression that Pakistan was in a fix over the project.
"We are very clear about this project. It is in our national interest to go ahead with this project," he was quoted as saying by Xinhua.
On pressure from the US, the spokesman said Islamabad knows about some concerns but "we expect and hope that all our friends including the US would show more understanding on the issue".