Prime Minister Yousaf Raza Gilani's comments came two days after the US special envoy to Pakistan, Richard Holbrooke, cautioned Pakistan not to "overcommit" itself to the deal because it could run afoul of new sanctions against Iran being finalized by Congress.

The deal has been a constant source of tension between the two countries, with Pakistan arguing that it is vital to its ability to cope with an energy crisis and the US stressing that it would undercut international pressure on Iran over its nuclear program.

Gilani said Pakistan would reconsider the deal if it violated UN sanctions, but the country was "not bound to follow" unilateral US measures. He said media reports that quoted him as saying that Pakistan would heed Holbrooke's warning were incorrect.

The UN has levied four sets of sanctions against Iran for failing to suspend uranium enrichment, a process that can produce fuel for a nuclear weapon. The latest set of UN sanctions was approved earlier this month.

The US has also applied a number of unilateral sanctions against Iran, and Congress is currently finalizing a new set largely aimed at the country's petroleum industry. Both houses have passed versions of the sanctions and are working to reconcile their differences.

The Obama administration last week added Iranian individuals and firms to a blacklist as part of US and European efforts to tighten the screws on Iran a week after UN approved sanctions against its nuclear program. The new US sanctions target insurance companies, oil firms and shipping lines linked to Iran's nuclear or missile programs as well as the Islamic Revolutionary Guards Corps and Iran's Defense Minister Ahmad Vahidi.

Pakistan and Iran finalized the gas deal earlier this month. Under the contract, Iran will export 760 million cubic feet of gas per day to Pakistan through a new pipeline beginning in 2014. The construction of the pipeline is estimated to cost some $7 billion.

Iran has already constructed 907 km of the pipeline between Asalooyeh, in southern Iran, and Iranshahr, which will carry natural gas from Iran's giant South Pars field. The pipeline was originally planned to connect Iran, Pakistan and India, but the latter pulled out of the project last year.

While US officials have expressed opposition to the deal, Washington acknowledges that Pakistan faces a severe energy crisis and has made aid to the energy sector one if its top development priorities. Electricity shortages in Pakistan cause rolling blackouts that affect businesses and intensify suffering during the hot summer months.

US opposition to the gas deal has also been tempered by Washington's reliance on Pakistani cooperation to fight Al-Qaeda and Taleban militants staging attacks against NATO troops in Afghanistan. The Pakistani military is also engaged in fierce battles with Taleban fighters along the Afghan border who have declared war against the state.