New Delhi, May 12: Prime Minister Manmohan Singh on Monday told defence scientists to speed up work on advanced technologies like hypersonic propulsions, unmanned vehicles and stealth machines to keep pace with current trends in warfare.

Singh said keeping pace with technologies like smart materials, micro and nano technologies and robotics would enable India to contend with emergence and growth of non-conventional and asymmetric warfare.

Stressing that self reliance and defence preparedness was not a case of numbers or percentages, the Prime Minister, addressing Technology Day function here, said scientists should clearly define strategic and critical areas in which development of national capability is a must.

"We must pursue this goal with determination and long term perspective," Singh said as he voiced his government's determination to broadbase the defence industry in the country.

The Prime Minister's comments came after the country's top defence scientist M Natarajan said that his organisation the DRDO was facing "definite capacity constraints".

Natarajan said "it is impossible for DRDO to cater to entire spectrum of products and services required by army, navy and air force and spoke for more active private industry participation in defence research."

The Prime Minister said the country's resources, infrastructure capabilities and intellectual capital--in both public and private sectors--should be treated as national assests and carefully nurtured and optimally utilised.