The U.N. mission in Congo says it has now evacuated more than 600 South Sudanese who fled with opposition leader Riek Machar into Garamba National Park in northeastern Congo last month.

A statement issued Monday said the latest group of 152 South Sudanese were evacuated and disarmed on Sunday, bringing the total to 634. The mission said 134 more South Sudanese remain in the park and warned that the situation risked becoming "a threat to peace in Congo and the sub-region."

Machar fled Juba, South Sudan's capital, in July after heavy fighting between his forces and forces loyal to President Salva Kiir. He slipped across the border to Congo in mid-August before being evacuated from Garamba with his wife, son and 10 aides on Aug. 17. Machar is now in Sudan.