NEW YORK, Feb 7: US scientists are quietly starting work on a new generation of nuclear arms meant to be more rugged and reliable than warheads in the existing arsenal, The New York Times reported on Monday.

About nine million dollars have been allocated so far for weapons designers at the three US nuclear weapons laboratories, the daily said, citing government officials and experts.

The initiative is expected to grow and could produce finished designs in five to 10 years. Congress and a future administration would then have to approve the development of prototype warheads.

Critics say the project could trigger a new arms race and topple bans on testing, while proponents say it could ultimately reduce the US nuclear arsenal, yet make it more robust.

US weapons builders have spent decades trimming the dimensions of originally massive bombs to make them easier to transport and more accurate, using the latest technologies and innovative methods. But now they want to emphasize reliability and long shelf life, and design weapons that are easy to manufacture.

The current arsenal of about 10,000 warheads is aging and the United States can no longer be certain of the reliability of the bombs due to international bans on testing.

"Our labs have been thinking about this problem off and on for 20 years," said John Harvey, director of policy planning at the National Nuclear Security Administration.

"The goal is to see if we can make smarter, cheaper and more easily manufactured designs that we can readily certify as safe and reliable for the indefinite future - and do so without nuclear testing."-AFP