Nikkei slumps to over 2-month low as yen climb hits exporters

* Nikkei drops 6 pct, Topix off 4.9 pct * Incentive to buy Japan shares seen erased by strong yen * Futures selling drags on cash market ahead of settlement By Ayai Tomisawa TOKYO, June 13 (Reuters) - Japan's Nikkei share average dived 6 percent and entered bear market territory on Thursday, extending early falls after the dollar fell to a 10-week low against the yen on worries the Federal Reserve may trim its stimulus programme. Selling was accelerated by a sell-off in futu