New York : Pfizer Inc has taken steps to ensure that none of its products are used in lethal injections, the largest US drugmaker said on Friday.

"We are enforcing a distribution restriction for specific products that have been part of, or considered by some states for, their lethal injection protocols," the New York-based drugmaker said on its website. "Pfizer strongly objects to the use of its products as lethal injections for capital punishment."

The move shuts off the last remaining open market source of drugs used in executions, following similar actions by more than 20 U.S. and European drugmakers, according to a report in the New York Times on Friday.

The list of products includes the powerful anesthetic propofol, the drug that caused the death of pop superstar Michael Jackson. The other Pfizer products the drugmaker said it will block from use in executions are pancuronium bromide, potassium chloride, idazolam, hydromorphone, rocuronium bromide and vecuronium bromide.

Pfizer's distribution restriction limits the sale of the seven products to a select group of wholesalers, distributors, and direct purchasers under the condition that they will not resell these products to correctional institutions for use in lethal injections, the company said.

Pfizer said it offers the products because they save or improve lives, and markets them solely for use as indicated in the product labeling.