"Upon repairs and modernisation the Tula will be tested and do shooting practice. Only after that can the sub join the fleet", the press service said.
"The submarine will be commissioned and, most probably, become part of the Northern fleet next year", Leonid Abramov, chief of the works' fifth repair and modernisation division, said by telephone.
In the beginning of May, the bulk of updating work will be over and the submarine will be taken out of the dockyard and launched, he said. Brought to the works for updating in 2000, the submarine has had its crucial systems - hydroacoustic and communication - replaced.
For lack of financing, it has proved to be impossible to manage overhaul and updating within the usual two years, Abramov said.
The Tula nuclear submarine was built 14 years ago.
A similar submarine of the Russian Navy is undergoing modernisation at the same Zvezdochka works. It is simultaneously filling an Indian order modernising a diesel submarine of the 877 design.