LINCOLN, Neb. (AP) — Pharmaceutical company Pfizer is demanding that Nebraska return any drugs manufactured by the company or an affiliate that the state plans to use in an execution.

State prison officials announced last week that it plans to use a new combination of four drugs in the execution of death-row inmate Jose Sandoval. No execution date has been set.

In an Oct. 4 letter, Pfizer said it "strongly objects to the use of its products as lethal injections for capital punishment," the Omaha World-Herald reported. The letter was among several documents released by the state Department of Corrections this week in response to public records requests from The World-Herald and the ACLU of Nebraska.

The company adopted a policy in 2016 that banned the use of its products and those of its affiliate, Hospira, in an execution. The 13 restricted products are intended to enhance and save lives, not take them, the company said.

Pfizer said it will reimburse the state for any drugs it returns. The company has corporate headquarters in New York City. It has its research headquarters in Groton, Conn.

Officials with the Nebraska Department of Correctional Services and the office of Gov. Pete Ricketts declined say whether the state has any Pfizer drugs.

The state spent $10,500 last month on four drugs for the execution, said Dawn-Renee Smith, a spokeswoman for the corrections department. While Smith didn't disclose the source of the drugs, she said they did come from a source in the U.S.

Nebraska plans to use diazepam, commonly known as Valium; synthetic opioid fentanyl citrate; paralytic cisatracurium besylate; and potassium chloride in its lethal injections.

Pfizer manufactures three of the four drugs, with cisatracurium besylate as the exception, according to a Pfizer spokesman.

Nebraska has struggled to obtain lethal injection drugs in recent years because of company bans.

Voters reinstated capital punishment last year, overriding state lawmakers who had abolished the death penalty. Nebraska hasn't executed anyone since 1997.