The stakes could not be higher for China, the largest investor in South Sudan's oil sector, as fierce fighting continues between forces loyal to President Salva Kiir and those of his former deputy.Some of the largest oilfields China operates are in areas controlled by fighters backing Riek Machar, the country's vice-president until he was sacked in July. Oil production has already dropped by 20% since the onset of the conflict three weeks ago and more than 300 Chinese workers have been evacuated. The spectre of their Libyan experience also weighs heavily on the Chinese minds -project after project now lies deserted because of