Tehran and Islamabad finalized a deal in June for the delivery of 750 million cubic feet of natural gas through the pipeline from the South Pars gas complex in the Persian Gulf.
India was included in initial plans for the project but stayed on the sidelines since 2008 because of pricing issues with Iran and concerns over the security of the pipeline through Pakistan.
Washington opposes the deal because of the economic benefits for Tehran, which was slapped with U.S. and European sanctions targeting Iran's energy sector in June.
A U.S. diplomat, whose name was redacted, was quoted by WikiLeaks as saying at a 2009 energy summit in Azerbaijan that it was "very unlikely" the gas pipeline would move forward, noting "the Pakistanis don't have the money to pay for either the pipeline, or the gas," the Press Trust of India said, quoting the watchdog.
Panelists at the energy summit said Iran was diverting too much gas to domestic consumers, which undermined the prospects of expanding the infrastructure for natural gas exports.
"A source asserted bluntly that Iranian political leaders are totally focused on domestic needs and personal jockeying, and are simply not interested in hearing about the value of optimizing foreign gas exports," a diplomatic cable read.
Tehran says first deliveries of natural gas through the pipeline are expected in Pakistan by 2015.