Pharmaceutical giant Pfizer has banned the sale of its drugs to be used for executions via lethal injection in the U.S., saying it manufactures drugs to save lives.

The company said in a statement that it "makes its products to enhance and save the lives of the patients we serve. Consistent with these values, Pfizer strongly objects to the use of its products as lethal injections for capital punishment."

As a result, it has enforced a distribution restriction for drug products that are used by states for lethal injection. These products are pancuronium bromide, potassium chloride, propofol, midazolam, hydromorphone, rocuronium bromide and vecuronium bromide.

Under the scheme, Pfizer will limit the sale of the seven chemicals to a select group of wholesalers, distributors and direct purchasers under the condition that they will not resell them to correctional institutions for use in lethal injections.

Government agencies that purchase the products must certify that the products will be used for medically prescribed patient care and not to be used for carrying out a death sentence. These agencies must also certify that the products are for their own use and they will not resell these.

Pfizer said it will consistently monitor the distribution of the seven drug products and vow to act if there is a violation of its policy.

According to the New York Times, more than 20 drug companies have already adopted the same restrictions.

"With Pfizer's announcement, all FDA-approved manufacturers of any potential execution drug have now blocked their sale for this purpose," said Maya Foa, who tracks drug companies for Reprieve, a London-based human rights group.

Some U.S. states have used straw buyers or tried importing drugs from abroad that are not approved by the FDA.

Other states have used electric chair, firing squad or gas chamber as method of execution if lethal injection drugs are not available, according to the report.