CHICAGO — The National Labor Relations Board on Friday issued 13 complaints against McDonald’s and some of its franchisees, calling them “joint employers” and alleging they violated labor rights of employees at various restaurants nationwide.

The labor board found merit in 86 cases filed in 13 cities including Chicago, New York and San Francisco. The cases allege McDonald’s and its franchisees retaliated against employees for “engaging in activities aimed at improving their wages and working conditions.”

Those activities included nationwide protests aimed at increasing wages and improving working conditions at the fast-food restaurants.

“While representatives of the Office of the General Counsel have been engaged in efforts to settle the matter with the parties, thus far, those efforts have largely been unsuccessful,” the NLRB said in a statement.

In a statement, McDonald’s said it is disappointed with the board’s decision and will contest the joint-employer allegation and the unfair labor practice charges.

“The National Labor Relations Board’s actions today improperly and dramatically strike at the heart of the franchise system — a system that creates economic opportunity, jobs and income for thousands of business owners and their employees across the country.”

McDonald’s has long maintained that its franchisees are independent owner-operators who set their own policies, including wages, while adhering to corporate standards in areas such as food preparation and restaurant design.

“This relationship does not establish a joint employer relationship under the law — and decades of case law support that principle,” the company said.