Markit and the Chartered Institute of Purchasing & Supply released their services purchasing managers' index (PMI) for the U.K. on Tuesday. The U.K. services PMI dropped to 55.8 in December from 58.6 in November, missing expectations for a rise to 58.9. That was the lowest level since May 2013.

A reading above 50 indicates growth in the sector.

Markit's chief economist Chris Williamson noted that "the loss of momentum towards the year end will no doubt fuel worries that the upturn is too fragile to withstand higher interest rates".