China's national welfare fund will start investing overseas very soon, with European markets among potential destinations, Reuters reported, citing a senior fund official.   "Money from the fund will start being invested abroad very soon. We will invest on the global financial markets, including European markets," said Reuters, quoted Xiang Huaicheng, head of the National Social Security Fund, as saying.   Overseas investments would be in instruments including stocks and bonds, Xiang said. He added that the amount to be invested would depend on market conditions, with no fixed quota to meet.   The fund had planned to invest between $500 million and $800 million outside the mainland by the end of 2006   In addition to strengthening the pension system, investment abroad may help Beijing reduce pressure for appreciation of the yuan as outflows of funds partially offset inflows of investment into the country.