MNA � Iranian Parliament Speaker Mohammad Bagher Ghalibaf voiced Iran's readiness for any humanitarian cooperation and assistance with Lebanon.

"I offer my condolences over the death of some people caused by catastrophic explosion in Beirut to the Lebanese people, government and parliament, Hezbollah and my brother Seyyed Hassan Nasrallah," wrote Ghalibaf in a tweet on Wednesday.

"As always, Iran is ready for any humanitarian cooperation and assistance," he added.

"I will be in contact with the Iranian and Lebanese officials to expedite this process," he said.

A massive explosion rocked Beirut, Lebanon, with the force of an earthquake followed by a shock wave that devastated much of the city.

The blast appeared to have followed a fire that had broken out in the city's port area, based on a video from the scene. The cause of the blast was immediately unknown. The force of the blast shook buildings, which were then hit again by the shock wave that blew out windows, sending shards of glass flying.

Beirut's governor Marwan Abboud called it a "national catastrophe" and the prime minister declared a day of mourning.