The U.S. company that makes a drug most states use in lethal injection announced Friday that it would no longer produce the powerful anesthetic, a decision that throws capital punishment in the United States into disarray.

The decision by Hospira of Lake Forest., Ill., was prompted by demands from Italy, which does not have capital punishment, that no sodium thiopental - which the company had planned to make at its plant outside Milan - be used for executions, officials said.

"We determined we could not prevent the drug from being diverted for use in capital punishment," said Dan Rosenberg, a Hospira spokesman. He noted that the company never condoned the drug's use for lethal injection and had hoped to continue making it for medical use.

Hospira's move will force states and the federal government to look for alternatives to the drug, which could require lengthy approval processes and result in costly, long-running legal challenges.

"This is clearly going to cause a problem for a lot of states," said Richard Dieter of the Death Penalty Information Center, a Washington-based group that does not take a position on the death penalty. "It's not clear how this is going to play out, but for some states it's going to put things into limbo or continue a limbo."

The announcement was praised by opponents of the death penalty for raising new questions about the procedures used for lethal injection.

"It's more evidence the house of cards is crumbling on this system," said Diann Rust-Tierney, executive director of the National Coalition to Abolish the Death Penalty.

But the decision was condemned by supporters of capital punishment. Some blasted another country's interference in the U.S. criminal justice system. Others said further delays in executions would anger the public. Surveys show that a majority of Americans support executions.

"I think it's going to anger a lot of people," said Michael Rushford, president and chief executive of the Criminal Justice Legal Foundation, a Sacramento group that supports the death penalty. "It would certainly bother someone whose daughter was killed by a convicted sex offender."

Thirty-five states, including Virginia and Maryland, execute prisoners. All use lethal injection, and until recently all but two had used a three-drug cocktail that included sodium thiopental to kill pain, pancurium bromide to paralyze the inmate and potassium chloride to stop the heart. Ohio and Washington state recently switched to using only sodium thiopental, which is also known as Pentothal.

Shortages of sodium thiopental began to emerge after Hospira stopped making it in August 2009 because of problems obtaining one of the main ingredients, prompting doctors to turn to alternatives and some states to delay executions.

The company had planned to shift production from a plant in North Carolina to a facility in Liscate, Italy. But after those plans became public, the Italian Parliament demanded the company ensure the drug would be used only for medical purposes.