India is moving ahead with efforts to modernize its submarine fleet amid concerns over China's growing naval presence in the Indian Ocean.
Prime Minister Narendra Modi's government accelerated the bidding process for six new diesel-electric submarines. These are in addition to six similar submarines under construction by a French company in Mumbai.
The push comes just months after a stand-off along the disputed border dividing India and China in the Himalayas, and as Chinese submarines have docked in Sri Lanka, the island nation off India's southern coast.
India told Sri Lanka that the Chinese presence there was unacceptable to New Delhi.
Beijing insisted the submarines were on refueling stops during anti piracy missions in the Indian Ocean and Gulf of Aden. This did not allay concerns in New Delhi.