A drone hit a refinery in Saudi Arabia's capital, Riyadh Thursday morning but oil supplies were not affected, Saudi state news agency SPA reported on Friday.

The attack caused a small fire that was controlled and did not result in any injuries or casualties, SPA said citing a statement by an energy ministry official.

"The refinery's operations and supplies of petroleum and its derivatives were not affected," the statement said.

It did not specify where the attack originated from.

The world's top oil exporter has faced frequent missile and drone assaults by Yemen's Iran-aligned Houthi group that has been battling a coalition led by Riyadh for seven years.

The Houthis have not announced any strikes against the kingdom in recent days and the Saudi-led coalition had not issued a statement regarding Thursday's incident.

"These repeated acts of sabotage and terrorism on vital installations and civilian structures ... do not just target the Kingdom but aim to undermine the security and stability of global energy supplies," the statement said.

Saudi Arabia accuses Iran of arming the Houthis and has blamed Tehran for past attacks including a 2019 strike on oil plants. Tehran denies doing so.

The conflict is widely seen in the region as a proxy war between Saudi Arabia and Iran.

Reuters report