The top UN envoy in Lebanon on Tuesday strongly condemned the bomb blast in Beirut, which injured dozens of people on the eve of Islamic holiest month of Ramadan, a spokesperson said.

Derek Plumbly, UN's special coordinator for Lebanon, said that such "cowardly acts of violence" aim at destabilizing the country and spreading fear among the population and are completely unacceptable, UN spokesperson Martin Nesirky told reporters here.

A car bomb attack occurred on Tuesday morning in an area controlled by the Lebanese Shiite militant party of Hezbollah in southern Beirut, injuring at least 53 people.

"Lebanon's leaders and political parties should rally together against such threats to their country's security and stability and work to reinforce the role of Lebanon's State institutions," Plumbly was quoted by the spokesperson as saying.

The Special Coordinator hopes Tuesday's incident will be thoroughly investigated and the perpetrators brought to justice as soon as possible, Nesirky said.