A bomb explosion in the Pakistani city of Lahore has left at least eight people dead and about 20 injured, officials say.

The February 23 blast struck an upscale shopping district, a spokesman for the Punjab provincial police said.

Police said the area had been sealed off and the cause of the explosion, which appeared to target a popular restaurant, was under investigation.

There were reports of a second explosion, but police said that turned out to be a false alarm.

The explosion came one day after authorities announced a national antiterrorism alert after the country was rocked by a spate of attacks that left more than 130 people dead.

On February 16, a militant detonated explosives at a Sufi shrine in Sindh province, killing 90 people. The Islamic State terrorist group claimed responsibility for that attack.

On February 13, a Taliban suicide-bomb attack in Lahore killed 13 people.