PARIS — Despite its relatively clean image, the European Union is losing at least 120 billion euros a year to corruption, and more than three-quarters of citizens believe that the problem is widespread in their countries, the bloc’s home affairs commissioner said on Monday.

The awarding of government business and political party financing are two areas dogged by shady dealings, Cecilia Malmstrom, the European commissioner for home affairs, said during a news conference in Brussels. But she said that less obvious sectors also had problems, including health care, where some patients were forced to pay under the table to obtain necessary treatments.

“Corruption undermines citizens’ confidence in democratic institutions and the rule of law, it hurts the European economy and deprives states of much-needed tax revenue,” Ms. Malmstrom said in introducing the report.

She said there were “some indications that the crisis has boosted” corrupt practices at the local level, but that the commission did not have sufficient historical data to be certain.