after falling as much as 5 percent earlier in the day -- as investors fretted the Chinese oil company would sweeten its offer. "On balance, I would not like to see CNOOC raising their bid too aggressively from here. I think they have offered a lot," said Edmund Harriss, fund manager at the Guinness Atkinson China & Hong Kong Fund, which owns about 11 million CNOOC shares. "The value for CNOOC will start to drop off quite significantly if they raise the bid too much further. I would not be comfortable with that." Since CNOOC announced its bid for Unocal in late June, its stock had jumped nearly 19 percent in the three weeks ended on Wednesday. CNOOC has been battling not just Chevron in this takeover battle, but growing opposition from some U.S. politicians, who have said it could jeopardize national security interests. The Chinese company has agreed to make guarantees it can meet all U.S. national security-related requirements and sell its U.S. assets if required, sources have said. CNOOC would "respond tactically" and immediately if the Unocal board rejects its bid or Chevron sweetens its offer, one source said. --SP 2240 Local Time 1940 GMT