The three countries signed the framework agreement with the Central Asian republic in Islamabad for the laying of the 56-inch-diameter TAPI pipeline, whose original cost in 2004 was estimated at half the current estimate, by 2015.

Pakistani Petroleum Minister Khwaja Asif said, "We believe it is still economically viable for the four countries even after the escalation in cost," the Press Trust of India reported.

The Asian Development Bank is providing financial backing, the report said. The cost overrun results mostly from sharp increases in steel prices and construction costs.

The gas will come from Turkmenistan's Daulatabad fields. It will be piped to Herat and Kandahar in Afghanistan, Multan in Pakistan and to Fazilka on the India-Pakistan border, the report said. The project is designed to supply 3.2 billion cubic feet of gas per day.