US rapper Lil' Wayne has vowed to defend marijuana and admitted that he uses the drug medicinally.

The rapper, whose real name is Dwayne Michael Carter Jr, spoke candidly about the substance during an interview with CBS News anchor Katie Couric.

Carter said he took marijuana to help clear migraines that “make me wanna kill myself”.

"I will stand up for marijuana any day... I'm a rapper. That’s who I am, Miss Katie, and I am a gangster and I do what I want,” he told Couric.

“And I love to smoke. And I smoke."

Carter has been arrested twice in the past three years on drug possession charges – the most recent arrest coming in January 2008.

He pleaded not guilty to the charges in a court in Arizona in May.

As previously reported, the rapper is currently preparing to release his seventh studio album 'Rebirth'.

The album, which marks Lil' Wayne's diversion into rock music, will be preceded by the single 'Prom Queen'.

(by Jason Gregory)