United Nations chief Antonio Guterres expressed concern Sunday over the resignation of Lebanese premier Saad Hariri, calling for security and stability.

Hariri, a protege of Riyadh, on Saturday announced his surprise resignation in a broadcast from the Saudi capital. He cited the "grip" of Iran -- an ally of Shiite group Hezbollah -- on the country, and also said he feared for his life.

"The secretary-general is concerned by news of the offer of resignation of Lebanon prime minister Saad Hariri," Guterres spokesman Stephane Dujarric said in a statement.

"He hopes all sides will focus their efforts on supporting the continuity of Lebanon's State institutions, in adherence with the constitution and safeguarding the country's security and stability.

"The United Nations remains committed to supporting the security, sovereignty and territorial integrity of Lebanon."

Iran has denied interfering in Lebanese internal affairs.

Hezbollah is the only organization in Lebanon to have retained its weapons after the end of the 1975-1990 civil war.