Iranian President Ebrahim Raisi will travel to Damascus next week, in the first visit to Syria by an Iranian leader since civil war broke out in the country in 2011.
Military and economic support from Iran and Russia helped Syrian President Bashar Al Assad reverse early losses to rebel groups and regain control of most of the country.
The Syrian daily Al Watan, which is close to the government, reported that Mr Raisi's visit would last two days, to be capped by a string of agreements, particularly on economic co-operation.
A senior regional source close to the Syrian government told Reuters that the recent warming of ties between Saudi Arabia and Iran, as well as an easing of Syria's isolation by fellow Arab states, had paved the way for the visit.
Saudi Foreign Minister Prince Faisal bin Farhan visited Damascus earlier this month in the first such trip since before the civil war began, while ministers from other Gulf Co-operation Council countries have also met to discuss Syria's potential return to the Arab League.
Besides military support, Iran has provided lines of credit to Damascus and imports phosphate from Syrian mines.
This month, regional sources revealed that Iran had secretly brought military equipment to Syria by disguising the transfers as part of the relief effort following the devastating February earthquakes in Syria and Turkey.
With reporting from Reuters
