The escalation of the crisis in Ukraine concerns German consumers and affects their confidence on the economic outlook, a survey showed on Tuesday.

German market research institute GfK said its forward-looking consumer sentiment indicator, based on its recent monthly survey of 2,000 consumers, was expected to remain at 8.5 points into May, the same level as in the previous two months.

"The upward trend in economic expectations indicator has come to an end, at least for the time being," said GfK in a statement.

The institute found that since February this year, the indicator for economic outlook has "more or less stagnated." In April, the indicator fell further.

"Events in Ukraine are clearly starting to have an impact. Germans appear to be slightly unsettled with regard to the further development of the domestic economy for the first time," the institute said.

Uncertainties in Ukraine also negatively affected German consumers' willingness to buy in April, despite the fact that their income expectations rose to the highest level since German reunification in 1991 due to a stable labor market and successful collective wage bargains.

"The escalation of tensions in eastern Ukraine have caused some consumers to fear that notable economic recovery could be weakened," it said, warning that consumers' worry would intensify if the situation in Ukraine continued to escalate and if western countries responded with stronger economic sanctions against Russia.