This week, it was revealed that Chambers, who has been at the helm for the past four years, had left the federation to take up a position closer to his home town of Peterborough. It is understood that he has been absent from the NFRN since Christmas.
Confusion has reigned at the federation since the departure of head of newspapers and magazines Stefan Wojciechowski in July.
It had come under fire for not being vocal enough and for missing key industry meetings. Chambers responded with a management team restructure, but the federation has continued to face pressure from newsagents.
In a statement, Chambers said: "I was pleased to have the chance to work alongside so many committed and passionate independent retailers and wish them and the federation every success."
He was also praised by his colleagues, with national president Parminder Singh saying: "The NFRN is a better place for having had Paul's services, with all his news industry and management experience.
"The National Executive Committee, along with the trustees and National Finance Committee plus all the 75 employees wish him well."
The NFRN added that the general manager position would be discussed at the next meeting of the NFRN's National Executive Council on 7 February and by its National Council on 14 February.