Authorities in Lebanon say they have thwarted a suicide bombing in one of the busiest neighbourhoods of the capital, Beirut.

Lebanon's National News Agency said the would-be attacker was wearing an explosive belt under his jacket, as he intended to blow himself up inside a Costa coffee shop on Hamra Street on Saturday evening.

Saad Hariri, Lebanon's prime minister, congratulated security forces on their successful operation in a tweet: "Our unity protects the nation and the people," he said.

The Daily Star newspaper reported that the cafe was filled with people socialising when the soldiers arrested the man at around 11pm local time.

Security sources told the paper the suspect was beaten up by soldiers during the arrest.

He was taken to a nearby hospital for treatment before interrogation, it added.

Al Jazeera's Imtiaz Tyab, reporting from Beirut, said security services identified the suspect as a man in his 20s from Sidon in the country's south.

"Security services visited his home and arrested two of his brothers, before taking laptops and other materials," he said.

Lebanon has been hit by a string of bomb attacks in recent years, some linked to the ongoing war in neighbouring Syria.

In June 2016, the army said it had arrested supporters from a local affiliate of the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group, planning attacks against busy areas.

The Hamra neighbourhood, a district known for shopping and nightlife, has not previously been hit by an attack.

Some of the deadliest blasts have targeted neighbourhoods sympathetic to the powerful Shia Hezbollah movement, which is fighting alongside the Syrian regime against the majority Sunni population.

The casualties in the blasts have been almost exclusively civilians.