Abuse of prescription painkiller have reached "epidemic" levels in the US, a government report says.

Overdoses of pain relievers cause more deaths than heroin and cocaine combined, the report has found.

It says sales and prescriptions of the drugs have risen sharply in recent years and this was linked to the rise in overdoses.

Narcotic painkillers are prescribed to relieve chronic pain but the drugs can be "highly addictive", the report says.

The report, published by the Centers for Disease Control and Prevention (CDC), said fatalities caused by narcotic pain relievers have more than tripled in the last 10 years - equivalent to 40 deaths a day.

Last year, a national survey on drug use and health showed that one in 20 Americans over the age of 12 said they had used painkillers for non-medical reasons.

Named as the fastest growing drug problem facing the US, narcotic painkillers are increasingly used recreationally - for the high they cause.

Surging sales

"Almost 5,500 people start to misuse prescription painkillers every day," said Pamela Hyde, administrator for the Substance Abuse and Mental Health Services Administration, a federal body.

Sales of the drugs to pharmacies and health care facilities have surged more than 300% since 1999, according to figures from the Drug Enforcement Administration.

But prescriptions of the drug have risen sharply too.

The report says enough medicine was prescribed last year to keep every American adult medicated for one month.

Florida was found to have the highest rate of sales of narcotic painkillers per person, almost three times the rate in Illinois, which had the lowest rate.

Officials believe state health policies can help reverse the trend.

The report recommends tracking prescriptions more carefully and cracking down on "pill mills" (clinics that prescribe drugs inappropriately) and "doctor shopping" (when patients collect prescriptions from several doctors).

"This highlights the importance of states getting policies right on preventing drug abuse," CDC Thomas Frieden told the Associated Press news agency.

In 2008, almost 15,000 deaths were caused by prescription painkillers, including the death of actor Heath Ledger.