More than 1.5 million people have been forced to leave South Sudan as intense fighting spreads, making it Africa’s largest refugee crisis, the U.N. refugee agency said Friday.

“With an extremely volatile security situation forcing more refugees to flee, the latest influx is straining the capacity of transit and reception centers, which are too small for the growing number of arrivals,” the Office of the U.N. High Commissioner for Refugees said.

The legal constraints posed by the ongoing civil war may make it difficult for Japan to keep its troops engaged in U.N. peacekeeping activities there.

The Ground Self-Defense Force has a camp in Juba. GSDF troops must be withdrawn from areas where the government determines combat is taking place in light of the war-renouncing Constitution and the principles set out for their participation in U.N. peacekeeping activities.

The opposition camp has accused the administration of Prime Minister Shinzo Abe of downplaying the seriousness of the South Sudan conflict by refusing to officially use the word “fighting” to describe battles last July that left hundreds of combatants dead.

In the GSDF’s daily activity logs for July, one entry said the soldiers have to “be careful about getting drawn into sudden fighting in the city” and also referred to the possibility of “the suspension of U.N. activities amid intensifying clashes in Juba.”

The Defense Ministry initially said the logs had been discarded but later revealed they had been “found” after a ruling party lawmaker revealed their existence on Twitter.

South Sudan’s refugee crisis is the world’s third-biggest after Syria and Afghanistan, the UNHCR said. The conflict has been spreading since intense fighting broke out again in and around Juba in July last year, following the collapse of a peace deal between the government and opposition forces, the agency said. The country gained independence in 2011.

“More than 60 percent of the refugees are children. . . . Recent new arrivals report suffering inside South Sudan with intense fighting, kidnappings, rape, fears of armed groups and threats to life, as well as acute food shortage,” UNHCR spokesperson William Spindler said.

In 2016, according to the UNHCR, more than 760,000 people fled from South Sudan to Uganda and other neighboring countries. Around 70,000 people have been forced to leave South Sudan so far this year.