In a phone conversation ahead of the planned signing on Friday of a US-Iran memorandum of understanding to end their war, Chinese Foreign Minister Wang Yi told Pakistan's Ishaq Dar that "it is foreseeable that, compared with the first stage, the second stage of negotiations will be more difficult".

Wang added that the United Nations Security Council "should also play a greater role" in supporting these talks, according to a statement from Beijing's foreign ministry.

"The current consensus is far from the final destination, rather it is a new starting point," Wang said.

"Achieving lasting peace in the Middle East and Gulf region still requires unremitting efforts from all parties," Wang said, adding that China was willing to work with Pakistan to promote peace.

Pakistani officials have previously said China, Islamabad's close ally and Iran's top trading partner, played a key role in supporting its mediation efforts.

Pakistan's foreign ministry said Wang and Dar agreed during their call to continue "engagement for the peaceful settlement of all outstanding issues", including the Strait of Hormuz maritime oil route that is subject to competing blockades that have roiled energy markets.

"They noted the importance of opening of the Strait of Hormuz for the global economy, energy security, and international trade," a ministry statement said.