A decision by pharmaceutical giant Pfizer to restrict distribution of its products used in lethal injections has cut off the last remaining approved source of drugs for carrying out the death penalty, experts said, according to AFP.

Capital punishment observers on Saturday hailed the move by New York-based Pfizer as "significant," noting that it highlights the pharmaceutical industry's opposition to the misuse of its products.

Pfizer said in a statement on its website that its mission includes making products to enhance and save lives, and therefore the company "strongly objects" to their use in lethal injections.