Ali Larijani is often viewed as a pragmatist and has an important role following the killing of Khamenei.
Dubai's airport authority says it authorised a limited number of flights as hundreds of thousands remain stranded.
Iranian Foreign Minister Abbas Araghchi holds calls with China's Wang Yi amid Israeli-US attacks on Iran.
Consumers are set to pay higher prices, but US producers could benefit, analysts say.
Israeli attacks on Lebanon have killed more than 50 people. It says the strikes are a response to Hezbollah rockets.
Saudi Defence Ministry says fire broke out at the embassy, but the compound sustained only 'minor' damage.
An unexploded US kamikaze drone was found on farmland in Western Iraq on Monday.
Predicting the total cost of the campaign is difficult, and experts warn the greater challenge may be inventory.
Tehran's historic Golestan Palace, a UNESCO World Heritage site, has sustained major damage after US-Israeli strikes.
US First Lady Melania Trump has presided over a UN Security Council meeting focusing on children in conflict.