The bill would make it illegal to possess, use, sell, manufacture, test and transport depleted uranium in all conventional munitions and armour within New Zealand and by agents of the New Zealand Government.
Mr Twyford said his bill was intended to send a strong message internationally that New Zealand did not support the use of depleted uranium.
Depleted uranium, a byproduct of uranium, is used by the military in hard armour piercing and bunker-busting missiles.
"Such weapons on impact ignites producing a fine radioactive gas that is so fine it can go through any gas mask," he said.
New Zealand troops and the Government do not use depleted uranium munitions but were exposed to their use while in combat overseas.
New Zealand troops are urine tested to detect the level of radiation in their system when they return to home after service.
"We legislated to ban cluster bombs and land mines in exactly the same way as a growing movement of countries that say these weapons are inhumane - they should not be used and should be banned."
Mr Twyford said there was not definitive proof of harm but evidence was strong it was the cause of birth defects and cancer in Iraq, and land contamination.
He said it was difficult to carry out scientific tests because military authorities would not provide coordinates of where they uranium weapons were used.
"It makes it extremely difficult to do the epidemiological studies that would conclusively demonstrate harm to the health of civilians and combatants.
"My bill is based on a precautionary principle - it says on the face of it these weapons are very threatening to human health."
He said Prime Minister John Key was awol on anti-nuclear and disarmament issues, and disbanded the role of Disarmament Minister.
National MP for Wairarapa John Hayes said National would not support the bill through to select committee.
Labour MP Maryan Street said it was socially irresponsible and inhumane for the National Party to refuse to allow the bill to progress to select committee.
The International Coalition to ban Uranium Weapons wrote an open letter to the National Party saying three United Nations recommendations had found depleted uranium is hazardous.
This view was shared by the World Health Organisation and the International Association for Environmental Philosophy.