UNITED NATIONS, Jan. 14 (Xinhua) -- The UN peacekeeping mission reported heavy fighting between government troops and opposition forces near a UN base in Malakal, South Sudan, a UN spokesperson said Tuesday.

Heavy machine guns and tanks were reportedly used in the fighting starting early Tuesday morning near the UN base in Malakal of Upper Nile state, Martin Nesirky said at a regular news briefing.

Stray bullets were reported to have landed inside the UN base and wounded people who were seeking shelter there. The UN Mission in South Sudan (UNMISS) said it is treating dozens of patients for wounds at its hospital.

According to the mission, the fighting has nearly doubled the number of internally displaced people seeking refuge at the UN base in Malakal to 20,000. Some 1,000 UN peacekeepers are protecting civilians at that base.

The UN peacekeepers are protecting a total of over 65,000 civilians at its bases across South Sudan.

The UN Refugee Agency (UNHCR) estimated that some 78,000 people have fled from South Sudan to neighboring countries such as Uganda, Ethiopia and Kenya since mid-December, when fighting broke out between forces loyal to South Sudanese President Salva Kiir and his former deputy Riek Machar. Subsequent conflicts in many parts of the world's youngest country have caused the deaths of over 1, 000 civilians.