Economic sentiment among the 19 members of the Eurozone fell during August to its lowest level since March, according to new EU data.
The European Commission's Eurozone Economic Sentiment Indicator (ESI) fell to 103.5 over the past month, from 104.5 in July - well below the 104.1 forecast by a Reuters poll of economists.
Confidence was down in four of the Eurozone's five largest economies, with France the only exception - the index there rose slightly in August.
"This suggests that the UK’s Brexit vote in late June has fed through to have a negative impact on Eurozone economic sentiment," said IHS Global Insight's chief UK and European economist Howard Archer.
The European Central Bank (ECB) said at the end of July that the consequences of the UK's vote in favour of leaving the EU had been "less marked" than previously anticipated.
However, Dennis de Jong, managing director of UFX.com, said ECB president Mario Draghi "won’t be overly concerned about the poor consumer confidence results released today as the downbeat sentiment has been part and parcel of the economic picture for some time now".
“The ECB will have been pleased to see strong data this morning from the two big beasts of the Eurozone – Germany and France – in addition to the positive signals from the EU’s manufacturing and services industries," said de Jong.
Today's data showed morale among industry managers fell to minus 4.4, as the assessment of current order books fell at its sharpest level since February 2009.
Confidence among managers in the services sector also dropped, to 10, caused by a fall in demand expectations.
The Commission's business climate indicator fell to an almost three-year low of 0.02 from 0.38 in July.
"Managers' assessments of past production, the level of overall and export order books deteriorated markedly," the Commission said.
Earlier this month data revealed that the Eurozone growth rate halved in the second quarter, with a slowdown in both France and Germany pulling down the overall economic performance of the bloc.