Since Thursday, aircraft carrying delegations have been touching down in Tehran’s Imam Khomeini and Mehrabad International Airports.

In May, Rouhani won re-election in a landslide victory after securing 57 percent of the votes and defeating his main contender Ebrahim Raeisi, the current custodian of the Holy Shrine of Imam Reza (PBUH).

The swearing-in ceremony is slated to be held (at Majlis Parliament) on Saturday.

On Thursday, Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei formally endorsed Rouhani as president.

Representatives from at least 100 countries are slated to partake in the ceremony.

By Saturday morning, officials from as many countries had reached Tehran for the ceremony, including: the European Union’s top diplomat Federica Mogherini; Britain’s Minister of State for the Middle East and North Africa Alistair Burt; Deputy Danish Foreign Minister Jonas Bering Liisberg; Deputy Italian Foreign Minister Vincenzo Amendola; Deputy Austrian Parliament Speaker Karlheinz Kopf; and the Netherlands’ former prime minister Wim Kok.

IRNA reported that Mogherini had held separate meetings with President Rouhani and Foreign Minister Mohammad Javad Zarif on Saturday.