UN peacekeepers help South Sudan civilians settle down at UN house in Juba, South Sudan, July 12, 2016. Tense calm returned to South Sudan's capital after the two leaders called on ceasefire and ordered all commanders to lay down arms and report to their unit bases. (Xinhua)

JUBA, July 28 (Xinhua) -- The UN refugee agency said Tuesday that influx of South Sudan refugees into Uganda was seriously straining on the capacity of collection and transit centers which are too small.

The UNHCR said the daily arrivals were averaging around 1,500 ten days ago but have risen to over 4,000 in the past week, expressing concern abut further surges in arrivals.

"The influx is putting serious strain on the capacity of collection points, and transit and reception centers, which are too small for the growing number of arrivals," UNHCR said in a statement received in Juba.

"During the course of the weekend, humanitarian organisations worked to decongest the collection points, as well as installing temporary shelters to increase capacities. UNHCR has deployed additional staff, trucks and buses to assist," it said.

Fighting in South Sudan that broke out on July 8 between rival factions loyal to Salva Kiir and Riek Machar has to date forced 37,890 people to flee the country to Uganda.

"In the past three weeks there have been more refugee arrivals in Uganda than in the entire first six months of 2016 (33,838)," UNHCR said.

The UN refugee agency said more than 11,000 refugees were staying in Elegu, northern Uganda, in a compound equipped to shelter only 1,000 people.

"Over the course of the weekend, the center was significantly decongested, with just 300 people sleeping there last night," it said.

It added that many of the refugees have been moved to the Nyumanzi Transit Centre, where they are receiving hot meals, water, shelter and other life-saving assistance, while others have been taken to expanded reception centers in Pagirinya. 

South Sudan's conflict, which erupted in December 2013, has produced one of the world's worst displacement situations with immense suffering.

Inside South Sudan, some 1.69 million people are displaced internally, while outside the country there are now 831,582 South Sudanese refugees, mainly in Ethiopia, Sudan, and Uganda.

According to UNHCR, an estimated 2,442 refugees were received in Uganda from South Sudan as of Monday, adding that 1,213 crossed at the Elugu Border Point in Amuru, 247 in Moyo, 57 in Lamwo, and 370 in Oraba. Another 555 were received in Kiryandongo Settlement.

"The majority of arrivals - more than 90 percent are women and children. People are coming from South Sudan's Eastern Equatoria region, as well as Juba and other areas of the country," the UN agency said.

It said the intensity of the violence has subsided in Juba since early July, but the security situation remains volatile.

The new arrivals in Uganda are reporting ongoing fighting as well as looting by armed militias, burning down of homes, and murders of civilians.