Consumer sentiment weakened in September to its lowest level in 21 months as worries around Brexit and rising energy and housing costs weighed.

Ireland is likely to be the fasting growing economy in Europe this year for the fifth year in a row, but the recovery has been uneven for some consumers, with only modest gains in purchasing power.

The KBC Bank Ireland/ESRI Consumer Sentiment Index slipped to 96.4 in September from 102.4 in August and 107.6 in July. 

The second consecutive decline ends a see-saw pattern of monthly changes since the index hit a 17-year high in January.

The survey's authors said the fall represented a clear drop in confidence among consumers and reflected a significant downgrade in views on household finances and the broader economic outlook. 

"There is little doubt that the increasingly loud and jarring ticking of the Brexit clock has unnerved Irish consumers," KBC Ireland's chief economist Austin Hughes said.

"The threat posed by a possible hard Brexit is notably amplified by high profile cost increases in areas such as light, heating and housing while many consumers may feel their personal circumstances are very remote from recent reports of a return to the boom," the economist added.

For the first time since December 2016, a larger share of consumers (23%) felt their financial circumstances had worsened over the previous year, than felt they had improved (21%), today's survey found.