North Korea's foreign minister Ri Yong Ho is due to visit Iran on Tuesday, Iranian media reported.
Ri is set to jet in as the United States reimposed sanctions on Iran following Washington's withdrawal from the 2015 deal to curb Tehran's nuclear programme.
The US is currently also pushing Pyongyang to scrap its nuclear capabilities after President Donald Trump and North Korea's leader Kim Jong Un agreed a vague commitment to "denuclearization of the Korean Peninsula" at their landmark summit in June.
North Korea's top diplomat will meet Iranian Foreign Minister Mohammad Javad Zarif, according to the conservative-aligned Fars news agency.
The report did not give any details of what will be discussed.
Ri is thought to have met with a high-level Iranian delegation at a meeting of the Non-Aligned Movement in Baku, Azerbaijan in April, according to the Korean Central News Agency.
A North Korean delegation also attended President Hassan Rouhani's inauguration in August 2017.
A United Nations Panel of Experts has expressed concern over collaboration between the two countries in the past, according to NK News.
In a 2017 report, it noted the presence of designated North Korean weapons traffickers living in Tehran and the similarity between missile designs in the two countries.