HONG KONG, June 20 (Reuters) - China shares extended losses on Thursday after a preliminary survey of manufacturing activity in the mainland in June came in at a nine-month low, aggravating jitters from a cash squeeze that is threatening to overwhelm the interbank market.
At 0601 GMT, the CSI300 of the leading Shanghai and Shenzhen A-shares listings was down 2.5 percent at 2,340.1 points, dipping below chart support at December lows at about 2,346. The Shanghai Composite Index was down 2 percent.
The flash HSBC Purchasing Managers' Index fell to 48.3 in June - the lowest in nine months - from May's final reading of 49.2, drifting further away from the 50-point level demarcating expansion from contraction. It was the weakest level since September.
China's interbank funding costs have surged recently, with the two shortest-term rates hitting record highs on Thursday, as the central bank again ignored market pressure to inject funds into the market, despite fresh evidence that the economy is slowing. (Reporting by Clement Tan; Editing by Kim Coghill)