Saudi Arabia has invited Iran's foreign minister to visit Riyadh, hinting at the possibility of a thaw between the two bitter rivals whose struggle for influence is evident in conflicts throughout the region.
Speaking at a news conference on Tuesday, Foreign Minister Prince Saud al-Faisal did not say when the invitation to Mohammad Javad Zarif had been made.
"Any time that [Zarif] sees fit to come, we are willing to receive him. Iran is a neighbour, we have relations with them and we will negotiate with them, we will talk with them," he said.
Zarif has visited other Gulf Arab states but he has not yet been to Saudi Arabia.
Sunni Muslim Saudi Arabia and Shia Iran have long supported competing factions in Arab countries, often along sectarian lines.
But Iranian backing for Syrian President Bashar al-Assad, and the aid Riyadh has given to rebels trying to oust him, has significantly raised tensions between the countries.
Saudi Arabia accuses Iran of fomenting unrest among the Shia majority in its neighbour Bahrain, and the Shia minority in its own Eastern Province, and also charges Tehran with plotting to assassinate its envoy in Washington in 2011.
Iran denies those accusations, as well as Saudi suspicions, shared with Western powers, that it has been using its declared civilian nuclear energy programme as a front to covertly develop an atomic bomb capability.
But since taking office as president in August, the moderate Hassan Rouhani has overseen a conciliatory shift in Iran's hitherto confrontational foreign relations, the Reuters news agency reported.
The most tangible result so far was Iran's November 24 interim nuclear deal with global powers.
Although Rouhani has a big voice in determining Tehran's foreign policy, the ultimate say is in the hands of clerical Supreme Leader Ayatollah Ali Khamenei.
"It's only a matter of time before Zarif takes up the invitation and goes to Riyadh," said Anoush Ehteshami, director of the al-Sabah programme for international relations at Durham University in Britain.
"It's a question of coordination at home with the leader. But it's inevitable that he go and important that he does. The Saudis are calling his bluff and saying 'come'."
'Not a rapprochement'
Suspicion between the two is deeply rooted, with Saudi Arabia's ruling family worried that Iran's clerical elite remains determined to export the message of its 1979 Islamic Revolution to Shia Muslims across the Middle East.
"Our hope is that Iran becomes part of the effort to make the region as safe and as prosperous as possible and not become part of the problem," the Saudi foreign minister said.
Iranian leaders regard Riyadh as a stooge for their US foes and remain angry at the Saudi role in backing Iraq during its eight-year war with Iran.
"It's not a rapprochement. All the issues are still there, [Iran's] interference that we have seen, all of it will come again on to the table," said Abdulaziz al-Sager, head of the Gulf Research Centre, based in Jeddah and Geneva.
"But it's better to meet your counterpart and to see the margin for compromise," he told Reuters.