Iran has suspended talks with Saudi Arabia, a website affiliated to Iran's top security body reported on Sunday, without giving a reason for the decision which comes as a fifth round of negotiations was due to start this week.
"Iran has unilaterally suspended talks with Saudi Arabia for now," Nournews said, adding that no specific date had been scheduled for a new round of talks.
Iran and Saudi Arabia started direct talks last year in an effort to mend their relations. Iraq's foreign minister said on Saturday his country would host a new round on Wednesday.
Riyadh in 2016 severed ties with Iran after Iranian protesters stormed the Saudi Embassy in Tehran following the execution of a revered Shia cleric in Saudi Arabia.
On Saturday, Saudi Arabia said it had executed 81 men in its biggest mass execution in decades. Activists and rights defenders said 41 were Shia Muslims from the eastern Qatif region, which has historically been a flashpoint between the Sunni kingdom and minority Shias, Reuters reported.
The two neighbors remain deeply divided over a set of regional issues, mainly the catastrophic Saudi-led war on Yemen.
Both Tehran and Riyadh have hinted that some progress was made in their recent negotiations.
Earlier this month, Saudi Crown Prince Mohammed bin Salman said that his country and Iran were "neighbors forever" and needed to work out their issues.
"We cannot get rid of them, and they can't get rid of us," he said, according to AFP.
"So it's better for both of us to work it out and to look for ways in which we can coexist," he added, expressing hope that "we can reach a position that's good for both countries".
Iran's foreign minister welcomed the comments as a sign of Riyadh's desire to restore severed ties.
"The recent remarks of a high-ranking Saudi official show their desire to establish bilateral relations with Iran, and we welcome that," Hossein Amir-Abdollahian said.
"These talks created a good atmosphere and brought results, though small ones, and we are pleased that Saudi Arabia has taken the path of dialogue," Iran's top diplomat said.
"We have different views and approaches on some issues in the region, but appropriate handling of differences by the sides can serve the interests of the two nations," he added.