Prime Minister Atal Bihari Vajpayee honoured some of the country's top defence scientists, including P Venugopalan, leading designer of the propulsion systems for Prithvi, Agni and BrahMos missiles, on the occasion of the fifth anniversary of the Pokhran nuclear tests.

May 11 is observed as National Technology Day to mark the nuclear tests.

The prime minister presented the annual Defence Research and Development Organisation Awards at a ceremony in Delhi on Sunday. 

Also on the honours list were Y P Pathak, the scientist who has developed Sarvarta, the Indian army's multi-hop, multi-span bridging system, which after being inducted into the armed forces is on the verge of winning export orders.

Pathak along with Venugopalan were among 10 academicians awarded the prestigious Scientist of the Year Award.

Dr G M Cleetus and his team were decorated with the Agni Award for Excellence in Self-reliance for developing a world-class mobile surveillance system, which won a contract from the Indian army in the face of stiff international competition.

After evaluation trials, the army ordered 1,171 of these radars, to be used in Jammu and Kashmir.

Veteran defence scientist and the country's leading expert on tanks M Natarajan was honoured with the Technology Leadership Award. He is considered the father of India's main battle tank Arjun.

Natarajan has followed its success by designing a self-propelled 52-calibre 155mm gun system for the Arjun.

Electronics and Radar Development Establishment, Bangalore, which did pioneering work on developing the Indra and Rajendra battlefield surveillance system radars, was declared the best DRDO laboratory bagging the prestigious Silicon Trophy.