Iran's President Mahmoud Ahmadinejad was travelling to Caracas on Thursday for the funeral of Venezuelan president Hugo Chavez, state television reported.
Ahmadinejad "will shortly leave Tehran for Venezuela to attend the funeral" of Chavez who died on Tuesday, the broadcaster announced in the early afternoon.
Friday's funeral of the firebrand leftist will be attended by several heads of state from Latin America and wider afield. On Thursday, mourners filed past his open casket as he lay in state in the capital.
Ahmadinejad on Wednesday paid tribute to his close ally for "serving the people of Venezuela and defending human and revolutionary values."
"Venezuela lost its brave, strong son and the world lost a wise and revolutionary leader," he added.
Tehran decreed a day of national mourning on Wednesday.
Venezuela is the Islamic republic's main ally in Latin America. Both countries are open in their hostility to the United States, and Tehran and Caracas have forged strong economic and political ties.
Chavez had visited Tehran 13 times since his rise to power in 1999, and Ahmadinejad has himself been to Venezuela six times after he became Iran's president in 2005.