JUBA (Reuters) - South Sudan’s civil war has mutated from a two-way fight between the president and his ousted former deputy to a fragmented conflict, making it harder to put it back together and peace more elusive, the top U.N. peacekeeper in the country said.

FILE PHOTO: UNHCR High Commissioner for Refugees Filippo Grandi (L) and David Shearer, Special Representative for South Sudan, listen to displaced people at a camp in Juba, South Sudan June 17, 2017. REUTERS/David Lewis

David Shearer, head of the 13,000-strong United Nations mission, welcomed signs that regional leaders were rejuvenating the peace process but said any initiative must include all factions, including that of former Vice President Riek Machar, and discourage the multiplication of armed groups.

South Sudan slipped into civil war in 2013, just two years after becoming independent from Khartoum, and some 4 million people – around one third of the population – have fled to neighboring countries or to pockets of relative safety.

The conflict, ignited by a feud between President Salva Kiir and Machar, has resulted in ethnic cleansing between the leaders’ respective Dinka and Nuer communities.

However, an escalation of fighting since last July that forced Machar to flee the country a month later has seen clashes spread to previously unaffected areas.

“The situation now is somewhat different to what it was a year ago, when it was largely bipolar,” Shearer told Reuters in an interview late on Monday.

“We are seeing a lot more of the conflict being played out at a very local level and that is worrying because as it fractures it becomes more difficult to try to put the pieces back together again.”

Fighting has in particular affected the southern Equatoria regions, previously largely spared violence. The spike in fighting resulted in South Sudan having the fastest growing refugee population in the world as civilians poured into Uganda.

Tens of thousands of civilians have fled to camps within South Sudan that are ringed by U.N. troops.

Peacekeepers have frequently been criticized for failing to do enough to protect civilians but the U.N. leadership says troops are obstructed and restricted by the army.

A combination of red tape and unwillingness meant it took eight months for the first of 4,000 U.N. reinforcements approved to start deploying after last year’s fighting.

PLACES AT THE TABLE

Analysts and diplomats say regional peace efforts have stumbled for much of the last year as Uganda, Ethiopia and Kenya adopted a more bilateral approach to the conflict.

But Shearer was optimistic that a recent meeting of regional leaders in Ethiopia would result in a more collective approach to the crisis.

“There was a sense that they want to rejuvenate the peace agreement and start moving that forward. That collective effort hasn’t been apparent for the last year,” he said.

Machar remains in exile in South Africa, excluded from the process.

Shearer said while regional leaders were reluctant to return to the “old formula” of insisting on a potentially explosive face-to-face between Kiir and Machar, there was recognition that Machar’s camp needed to be represented in talks and he could too, further down the line.

The U.N. chief said there was a delicate balance between a rejuvenated and broadened push for peace and creating incentives to add to the plethora of armed groups.

“What we don’t want to do is to encourage a greater degree of conflict or arming of groups in order to be relevant and have a place at the table,” he warned.