0804 GMT December 03, 2020
Al-Sulaiti returned to the Iranian capital on Friday after a 20-month hiatus that started in January 2016, Tasnim News Agency reported.
Following in the footsteps of Saudi Arabia, Qatar recalled its ambassador to Tehran in January last year after Riyadh cut ties with the Islamic Republic over protests outside its embassy in Tehran and consulate in Mashhad against the kingdom's execution of senior Shia cleric Ayatollah Nimr al-Nimr.
Unlike Riyadh, however, Doha had not cut all diplomatic ties with Iran.
In a statement on Wednesday, the Qatari Foreign Ministry announced that the Persian Gulf Arab country was upgrading its ties with Iran back to the ambassadorial level.
The decision to elevate relations with the Islamic Republic comes amid a diplomatic rift between Qatar and several Arab countries, including Saudi Arabia, the UAE, Egypt and Bahrain.
The Arab countries allied with Saudi Arabia blame Doha of interfering in the domestic affairs of other states and sponsoring terrorism, an accusation Qatar has rejected as "groundless".
The diplomatic crisis, the worst since the 1990 invasion of Kuwait by Iraq and the subsequent Persian Gulf War, has seen the Arab nations cut ties with Qatar, which hosts a major US military base and will be the host of the 2022 FIFA World Cup.
Doha has been receiving fresh food supplies from Iran, which has also allowed Qatar's national carrier to use its airspace.