LONDON, Dec 16 (Reuters) - European stocks fell and German Bund yields hit a record low on Tuesday after data showed Germany's private sector grew at the slowest pace in 18 months in December.

Markit's flash composite Purchasing Managers' Index (PMI), which tracks activity in the manufacturing and services sectors that account for more than two-thirds of the economy, fell to 51.4 in December from a final reading of 51.7 in November.

That was above the 50 line denoting growth for the 20th month running, but it was the lowest reading since June 2013 and far below levels seen earlier this year.

Europe's FTSEurofirst 200 index extended its losses after the data to trade 0.67 percent down on the day at 1281.95. Ten-year Bund yields fell to a new low of 0.608 percent, according to Reuters data.

(Reporting by London Markets, editing by Nigel Stephenson)