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.

"We couldn't meet the Italian demands, and we were concerned if we couldn't our Italian facility and employees could face liability," Rosenberg said. He said he could not elaborate on why the company could not resume producing the drug in North Carolina.

Oklahoma last year became the first state to switch to another method, replacing sodium thiopental with pentobarbital, which is widely used to euthanize animals. After winning a court challenge to that decision, the state has executed three inmates since December.

In Virginia, which has carried out 108 executions - the second-highest number in the nation - since the reinstatement of the death penalty in 1976, officials said they were looking for alternatives. The state uses both the three-drug combination including sodium thiopental and the electric chair.

"We are in the same position as many other states and are looking into all options," said Larry Traylor, a spokesman for the Virginia Department of Corrections. Ten men are on death row in Virginia, but no execution dates have been scheduled by the courts, authorities said.

In Maryland, where lawmakers have debated in recent years whether to abolish capital punishment, the use of the death penalty has been on hold since December 2006, when the state's highest court ruled that the procedure for carrying out executions had been improperly adopted. State lawmakers have scheduled a Feb. 16 hearing on new proposed regulations.

After shortages of the drug emerged, several states, including California and Arizona, obtained supplies from a manufacturer in Britain. But officials in Britain, which also does not have the death penalty, have demanded that any future shipments to the United States not be used for executions.

Officials in Texas, which conducts the most executions in the nation, said they would "explore other options, including possibly seeking an alternate drug." Texas has four executions scheduled: two in February, one in May and one in July.

"At this time, we have enough sodium thiopental on hand to carry out the two executions scheduled in February. In March, our supply of this particular drug is set to expire," a statement from the state's Department of Criminal Justice said. There are 317 men and women on death row in Texas.

Traci L. Billingsley, a spokeswoman for the federal Bureau of Prisons, said the agency has not "assessed the impact of the Hospira announcement." There are 60 inmates on federal death row. The federal government's method of execution is by injection.

Rushford said Friday's announcement indicated the desperation of those opposed to the death penalty.

"The anti-death penalty advocates are focusing on the drugs as a way to prevent execution. I guess if we were using a firing squad, they would go after the Remington company for their bullets. It's an interesting tactic," he said.

But others welcomed the development, predicting it could lead to a broad reexamination of whether the methods used are cruel.

"I am pleased that a drug company has recognized the political ramifications of the sale of its product, even if that realization was ultimately forced by another country's laws and politics," said Deborah W. Denno, a professor at Fordham University School of Law.

Staff writers Maria Glod and Jerry Markon contributed to this report.