(fixes spelling of Defence Ministry spokesman in paragraph 2)

BEIJING, Sept 25 (Reuters) - China said on Thursday it will send 700 troops to join a U.N. peacekeeping mission in South Sudan, where fighting has threatened Beijing’s oil investments.

The troops will assist the U.N. with protecting citizens and humanitarian workers and in other security-related activities in the newly independent country, said Defence Ministry spokesman Geng Yansheng in a statement.

The location of the troops and the timing of the deployment were still being negotiated, the statement said.

U.N. officials have previously said it would be the first time China had contributed a battalion to a U.N. peacekeeping mission. Last year China sent a smaller “protection unit” to join a U.N. mission in Mali.

China has more than 1,800 peacekeepers in Africa, China’s Foreign Ministry said earlier this month.

China has played an unusually active diplomatic role in South Sudan.

About five percent of China’s oil imports came from South Sudan when it was pumping at full tilt. The state firm China National Petroleum Corp. has a 40 percent stake in a joint venture developing the fields.

The nine-month-old rebellion in South Sudan threatens Beijing’s oil investments. Chinese officials have worked with Western diplomats to help regional African mediators push for a halt to the fighting. (Reporting By Megha Rajagopalan; Editing by Nick Macfie)