Lithuania decommissioned the Ignalina plant's first power-generating unit in 2004 as part of a deal to join the EU, and pledged to shut down the second reactor by late 2009, in line with EU nuclear safety requirements.
The Ignalina nuclear power plant is of a similar design to the power plant that exploded in 1986 in Chernobyl, Ukraine.
The shutdown of the Soviet-era power station, which has been providing about 70% of Lithuania's electricity, could result in energy deficit in the region.
Lithuania strives to cooperate with its neighbors to secure its energy system by diversifying energy supply sources.
The replacement for Ignalina, due to be built as part of a $3-4 billion joint project with Poland, Estonia and Latvia is unlikely to be ready before 2015. Lithuania has been reluctant to close the plant and increase its reliance on Russia for energy before its replacement can be commissioned.