New Delhi, Aug 10 (IANS): The nuclear reactor's activation on India's first n-submarine INS Arihant "represents a giant stride in the progress of our indigenous technological capabilities", said Prime Minister Manmohan Singh Saturday.

Manmohan Singh, in a congratulatory message, lauded the scientists and defence personnel for activating the reactor on INS Arihant.

"I am delighted to learn that the nuclear propulsion reactor on board INS Arihant, India's first indigenous nuclear powered submarine, has now achieved criticality," he said.

"I extend my congratulations to all those associated with this important milestone, particularly the Department of Atomic Energy, the Indian Navy and the Defence Research and Development Organization," he said.

The prime minister said: "Today's development represents a giant stride in the progress of our indigenous technological capabilities. It is testimony to the ability of our scientists, technologists and defence personnel to work together for mastering complex technologies in the service of our nation's security".

"I look forward to the early commissioning of the INS Arihant."

India's activation of the atomic reactor on board the INS Arihant is a major step towards operational deployment of the indigenous nuclear submarine.

The nuclear reactor on Arihant was made critical Friday night and the submarine was on its own power now.