WASHINGTON - US fast-food workers on Thursday staged protests in 100 cities including Washington D.C., New York and Detroit to call for an increase of the federal minimum wage, local media reported.

The protest came one day after US President Barack Obama pressed Congress to raise the federal minimum wage, which currently stands at $7.25 per hour.

Speaking Wednesday during an event hosted by the Washington-based think tank the Center for American Progress, Obama said income inequality was the "defining challenge" for the United States, and the combined trends of increased inequality and decreasing mobility posed a fundamental threat to the American Dream.

Obama has repeatedly proposed an increase of federal minimum wage, but top Republican lawmakers opposed it claiming that it will add to the operating costs of business owners.