LONDON — The furniture giant Ikea joined a growing list of brands that have been touched by Europe’s food scandal on Monday and withdrew its signature Swedish meatballs from its markets and cafeterias across most of Europe after one batch was found to contain traces of horse meat.

Ikea’s decision — which followed a recall by the Swiss food maker Nestlé last week — demonstrated that even closely guarded brand names have found themselves vulnerable.

In weeks of tracing the problem, European Union and national officials have conceded that their oversight had not been aimed at authenticating food products. Now that governments and companies have undertaken more extensive testing, the results appear to indicate that food adulteration may be more commonplace and widespread than previously believed.

“Clearly there has been fraud on a massive scale across multiple countries in the E.U.,” Simon Coveney, the agriculture minister for Ireland, which holds the union’s rotating presidency, told a news conference after a meeting with colleagues in Brussels on Monday.