LONDON, Sept 14 - The dollar extended its slide on Friday, tumbling more than one percent to six-month lows against the yen as flight out of the greenback into safe-haven currencies triggered key chart levels. The dollar fell more than one percent to lows around 117.40 yen , but quickly pared losses after Japan warned it was watching the currency market closely and would take appropriate steps if needed. "This is basically a technical move. The dollar has broken levels around 118.35 which was a very key level," said Ian Stannard, foreign exchange strategist at BNP Paribas. "But the risks of joint intervention by G7 countries are increasing so that would keep the dollar decline in check," he added.