A North Korean economic delegation has reportedly returned home from a rare trip to Iran.

According to the North’s state Korean Central News Agency(KCNA) on Friday, the delegation led by external economic relations minister Yun Jong-ho, arrived in Pyongyang on Thursday. The report did not elaborate further on the visit. 

The KCNA earlier reported on the delegation’s departure for Iran on April 23. 

There were speculations that North Korea and Iran, which have long been suspected of cooperating on ballistic missile and nuclear programs, discussed bilateral military cooperation during the visit. 

However, the spokesperson for Iran’s foreign ministry dismissed the speculations as “biased and baseless” on Monday, saying that the delegation attended an Iranian expo in Tehran and held trade talks with representatives of the government and the private sector.