The award was first secured two years ago and council officials say hanging on to it shows the libraries' ongoing commitment to providing excellent customer service.

There were more than 969,164 visitors to the city's libraries last year with the service made up of 10 static and two mobile facilities.

The city council's cabinet member for community services Councillor Matthew Lee said: "The Charter Mark scheme is designed to help organisations focus on, and improve, their customer service and delivery to users.

"Being awarded the Charter Mark for another year is a huge achievement for our libraries' staff and demonstrates their commitment to customer service."

The Charter Mark is the Government's "gold standard" for excellence in customer service.

To secure the award libraries have to demonstrate, among other things, clear service and performance standards in consulting with customers, active engagement with customers, partners and staff and a service that is fair and accessible to everyone and promotes choice