Disappointing drug advocates, Pope Francis has set the record straight saying the secret to his energy is not "drugs".

Pope Francis, 78, made the declaration while touring three Latin American countries – Ecuador, Bolivia and Paraguay.

When prompted by a journalist to spill the beans on how he has such high energy levels, Pope Francis replied: "You would like to say that I take drugs!

"Mate is what helps me. I have never tried coca. That should be made clear."

Mate is a traditional South American drink infused with caffeine that is famous in Argentina, the Pope's native country, reported AFP News.

Coca, which is native to western South America, is famous for its psychoactive alkaloid, cocaine, however chewing on coca leaves or drinking coca tea does not give the intense high that is experienced when smoking cocaine.

Earlier Pope Francis had said that the legalisation of marijuana and other recreational substances is an ineffective method to tackle drug use.

"Let me state this in the clearest terms possible: the problem of drug use is not solved with drugs! [Legalising the drugs is a] veiled means of surrendering to the phenomenon," said the Pope.

'I overlooked the middle class'

Pope Francis also admitted on 12 July to overlooking the middle class with his entire focus being on the poor.

"It's a good correction, thanks," Pope Francis told a German journalist, Ludwig Ring-Eifel, while returning to the Vatican from his Latin America trip.

"You are right. It's an error of mine not to think about this."