US fastfood chain Burger King has hired investment banking firm Trinity Capital to help franchisees to return their operations to profitability.

"Clearly one of the most pressing issues facing the Burger King system today is the financial distress of a number of our franchisees," Burger King chief executive Brad Blum was quoted by Reuters as saying.

Burger King's agreement with Trinity Capital follows the early December bankruptcy filing by AmeriKing, one of Burger King's largest franchisees.

Blum said Burger King will pay the fees for Trinity Capital to act as "a neutral third party and negotiate the quickest possible resolution among the franchisees, lenders and Burger King Corp." He said Burger King wants its franchisees to become profitable enough to be able to invest in improving service and appearance at their restaurants.

Less than 20% of Burger King's some 1,000 worldwide franchisees will be eligible for the services, Burger King spokesman Robert Doughty told Reuters.

"We want to get people focused on restaurants' operational excellence," he said. "They can't do that because of their financial condition."

Some 91% of Burger King's 11,450 worldwide restaurants are owned and operated by independent franchisees.