Shi'ite-dominated Iran expressed condolences on Friday over the death of Saudi Arabia's King Abdullah bin Abdulaziz, the semi-official Tasnim news agency reported.
Relations between Tehran and Riyadh have been tense ever since Iran's 1979 Islamic revolution brought to power Shi'ite clerics opposed to the conservative Sunni Muslim kingdom.
"Iranian Foreign Minister Mohammad Javad Zarif will attend the late king's funeral ceremony in Riyadh," Tasnim quoted Foreign Ministry spokeswoman Marziyeh Afkham as saying.
King Abdullah died early on Friday and his brother Salman became king, the royal court in the world's top oil exporter said in a statement.
Zarif had planned to visit Saudi Arabia previously but delayed his trip in protest at Riyadh's refusal to cut crude oil output and help lift world oil prices, an Iranian official said last week.
Tehran and Riyadh support rival sides in several regional wars and disputes including Bahrain, Yemen, Syria, Iraq and Lebanon, but a security aide to Supreme Leader Ayatollah Ali Khamenei said on Tuesday that Iran was "ready for ... clear and continuous talks spanning the whole range of mutual interests with Saudi Arabia."