With the Scorpene submarine project getting delayed, India is holding talks with Germany to upgrade the capabilities of its HDW underwater vessels.
Discussions in this regard are being held between the two countries at the ongoing fifth Indo-German Defence Committee meeting here, Navy sources told agency.
"Our submarine fleet is depleting and numbers are expected to go down with the delay in the Scorpene project.
The talks are on with German officials to upgrade the existing fleet of four HDW submarines," they said.
The HDW submarines, also known as Shishumar class in the Indian Navy, were procured from Germany in the mid 80s and the last of it was inducted in 1990-91.
Under its Project-75, Navy was planning to induct the first Scorpene submarine by 2011 but due to delays on part of MDL and the Navy, the first induction is expected to take place only by late 2015.
Due to the delays in the project, the Government has decided to upgrade the existing fleet of Russian origin Kilo class and the German vessels.
A few of the Kilo class submarines have already undergone upgrades in Russia and have been fitted with new weaponry and other superior sensors and systems.
During the meeting, the two sides will also hold talks to enhance cooperation in anti-piracy operations and patrolling of important sea routes in the pirate-infested areas, sources said.
The two countries have so far held discussions on enhancing military to military cooperation through joint exercises and training drills.