WASHINGTON (AFP) - The US government wants states to crack down more on people driving under the influence of alcohol by lowering the permitted blood-alcohol limit.

It is now at 0.8 gram of alcohol per liter of blood.

The National Transportation Safety Board said Tuesday it should come down to 0.5. That would put the US in line with most other countries in the world.

The NTSB said research has found that with a level of 0.5 most drivers experience a decline in both cognitive and visual functions, significantly increasing the risk of a serious crash.

More than 100 countries in six continents limit the blood-alcohol content level to 0.5, the board said. It wants the 50 American states to follow their example.

"Most Americans think that we've solved the problem of impaired driving, but in fact, it's still a national epidemic," NTSB Chairman Deborah A.P. Hersman said.

"Each year in the United States, nearly 10,000 people are killed in crashes involving alcohol-impaired drivers and more than 173,000 are injured," the NTSB said in a statement.

It added: "Since the mid-1990s, even as total highway fatalities have fallen, the proportion of deaths from accidents involving an alcohol-impaired driver has remained constant at around 30 per cent. In the last 30 years, nearly 440,000 people have died in alcohol related crashes."