BEIJING, July 17 -- A Foreign Ministry spokesman said Thursday that the relocation of HYSY 981 rig is a normal offshore operation and has nothing to do with external factors.

Hong Lei made the comment in response to U.S. State Department spokeswoman Jen Psaki's remark on China's removal of the oil rig. Psaki said on Wednesday that the U.S. welcomes China's removal of its oil rig from a location near the Xisha Islands in the South China Sea to an area closer to Hainan Island.

"I'm not going to speculate on China's reason for withdrawing its rig," she said, adding that the United States supports a voluntary freeze on provocative unilateral action in support of further implementation of the 2002 code of conduct for the South China Sea between China and ASEAN.

Hong said the HYSY 981 rig has completed drilling and is set to continue its work off south China's island province of Hainan.

He reaffirmed that China will protect its territorial sovereignty and marine rights and interests.

China is committed to maintaining peace and stability in the South China Sea, he said, calling for an objective and fair attitude from relevant countries toward the South China Sea issue.

China National Petroleum Corp. (CNPC) and China Oilfield Services Limited began the drilling operation off Zhongjian Island, one of the Xisha Islands, on May 2. Work was completed on July 15.

The CNPC has been exploring the area since 2004.