US sandwich chain Quiznos has filed for pre-packaged bankruptcy.

The chain said restructuring will reduce its debt by more than $400m (£240m), and has received $15m in new financing from its senior lenders.

All but seven of its nearly 2,100 restaurants are independently owned and operated by franchisees, and, according to Quiznos, will not be affected by the bankruptcy.

In a statement, Stuart Mathis, chief executive, said the plan was also intended to increase flexibility to strengthen performance and revitalise the brand.

Mathis said: “The actions we are taking are intended to enable us to reduce our debt, execute a comprehensive plan to further enhance the customer experience, elevate the profile of the brand and help increase sales and profits for our franchise owners.

"As we move through this process, we will continue working with our franchisees in the US and internationally to strengthen our brand, build momentum and improve growth and profitability, as we position Quiznos for future success.”

He added that its international operations will continue to conduct business as usual.

Earlier this year, Quiznos announced it was re-entering the UK market, and opened an outlet outside Aldgate East Tube station last month. A further nine are planned to open during 2014.