TUNIS, Sept 29 (Reuters) - Tunisia's central bank kept its key interest rate unchanged at 4.25 percent, the bank said on Thursday.

The bank last cut its main interest rate in October, from 4.75 percent, in a bid to boost economic growth as inflation fell. The inflation rate was 4.9 percent in 2015, down from 5.5 percent in 2014.

(Reporting By Tarek Amara; Editing by Angus MacSwan) ((tarek.amara@thomsonreuters.com;))