Iran on Monday cited "significant progress" in talks with world powers in Vienna on reviving the 2015 nuclear deal.

Foreign Ministry spokesman Saeed Khatibzadeh said Tehran insists on lifting all sanctions that contradict the nuclear deal.

The spokesman, however, did not provide any details about the nature of the progress in the talks.

Negotiations are underway in Vienna between delegations from Russia, China, Germany, France, the UK and Iran. Washington is indirectly involved in the talks.

The nuclear deal was signed between Iran and world powers in 2015, under which Iran was required to limit its nuclear activities in return of sanctions relief. However, in May 2018, former US President Donald Trump announced withdrawal from the landmark deal, followed by sanctions.

In recent years, Iran has ramped up its nuclear activities as a countermeasure, stirring up tensions with the West.

Meanwhile, Khatibzadeh said Iran is ready to hold talks with neighboring countries, in a reference to Saudi statements about preparations to hold a fifth round of talks with Tehran.

He said the success of the talks with Saudi Arabia depends on a real willingness from Riyadh to do so.

On Saturday, Saudi Foreign Minister Prince Faisal bin Farhan Al-Saud said his country plans to hold a fifth round of direct talks with Tehran.

“We are looking to schedule a fifth round of direct talks with Iran despite a lack of substantive progress so far,” bin Farhan said in a speech at the Munich Security Conference.

Tehran and Riyadh severed diplomatic relations in January 2016 following an attack on the Saudi Embassy in Tehran after Shia cleric Nimr al-Nimr was executed by Saudi authorities.

The relationship between the two rivals deteriorated further after Iran in September 2016 accused Riyadh of deliberately causing the death of around 400 Iranian pilgrims in a 2015 stampede in the Muslim holy city of Mecca.

The two sides have since been engaged in a strong regional rivalry, often accusing each other of waging a proxy war for regional influence.

The two regional rivals held four rounds of talks hosted by Iraq in an effort to normalize their relations and ease tensions between the two neighbors.