Pakistan is coping with a natural gas shortage by pursuing two pipeline options. Washington supports an option from Turkmenistan that would travel through Afghanistan, while Tehran has pressed for its version since its initial inception in the 1990s.
Pakistani Prime Minister Syed Yousuf Raza Gilani said following talks with Afghan and Iranian officials that Islamabad wants a diverse natural gas sector.
"We will definitely go ahead with the (Iranian) project," he was quoted by Iran's state-funded broadcaster Press TV as saying.
Islamabad has moved closer to the Iranian project despite Washington's objections. Authorities in the Pakistani government suggested land surveys were under way for their part of the pipeline.
The Turkmenistan pipeline has the support of the Asian Development Bank though security and pricing issues continue to overshadow developments.
Victoria Nuland, a spokeswoman for the U.S. State Department, had said the Iranian natural gas pipeline was "a bad idea and we're continuing to talk to Pakistan about that."