Iranian foreign minister Mohammad Javad Zarif was due to visit Qatar on Monday, a ministry spokesman said, for talks on relations between Tehran and Doha that have caused tensions in the Gulf.
Mr Zarif left Tehran on Monday morning for Oman and was to head to Doha in the afternoon, said Iranian foreign ministry spokesman Bahram Ghassemi.
It will be Mr Zarif's first visit to Doha since the UAE, Saudi Arabia, Bahrain and Egypt cut ties with Qatar in June, for backing extremism and fostering ties with Iran.
Upon his arrival in Muscat, Mr Zarif was met by Yusuf bin Alawi bin Abdallah, the minister responsible for foreign affairs.
Topics of discussion with officials included the wars in Iraq, Syria and Yemen, according to Iran's semi-official Isna news agency.
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Mr Zarif called Oman's relations with Iran "exemplary" while on his visit.
"We also live in a very difficult neighbourhood and we want to engage in continuous consultation," he told Omani state television.
Oman has traditionally had closer ties with Iran than its neighbours and has maintained relations with Qatar throughout its dispute with other Arab countries.
In Qatar, Mr Zarif is to meet Emir Sheikh Tamim bin Hamad Al Thani and Qatari foreign minister Sheikh Mohammed bin Abdulrahman Al Thani.
Mr Ghassemi said talks would focus on relations in the Gulf, economic co-operation and the latest developments in Syria, Iraq and Yemen.
Speaking in Paris last week, Qatari foreign minister Sheikh Mohammed said moves by Qatar's rivals, including the cutting of trade and transport links, were pushing Doha into closer ties with Tehran.
Qatar said in August it was restoring full diplomatic relations with Iran. Doha, along with other Arab Gulf states, had pulled its ambassador from Tehran in January 2016 following attacks by protesters on Saudi diplomatic missions in Iran.