FILE PHOTO: Security forces stand around the headquarters of Libya's foreign ministry after a suicide attack in Tripoli, Libya December 25, 2018. REUTERS/Hani Amara/File Photo

TRIPOLI (Reuters) - Rival militias clashed in the Libyan capital Tripoli on Wednesday and at least five people were killed and 20 wounded, the health ministry said, splintering a four-month-old, U.N.-brokered ceasefire.

Armored vehicles could be seen in southern Tripoli where militia groups had fought for a month until September, part of the widespread factional conflict plaguing Libya since the 2011 uprising that toppled Muammar Gaddafi.

A United Nations-engineered ceasefire agreed then had managed to hold for the most part until now.

But on Wednesday a militia known as the 7th Brigade, or Kaniyat, and a collection of factions called Tripoli Protection Force fell back into fighting in the same southern district.

The 7th Brigade and some allied groups triggered the August fighting in a bid to challenge the dominance of four “super militias”, including the Tripoli Protection Force, in the streets of the capital.

The U.N. mission in Libya warned in a statement against any breach of the ceasefire deal.

“Any party initiating a confrontation will be held fully responsible,” it said.

The internationally-recognized government in Tripoli, backed by the United Nations, has been working on a new security plan since the ceasefire deal but achieved little as Libya, long a major oil producer, lacks a national police force or army.