Image copyright AP Image caption The condemned will be strapped in tight, while the chemicals are prepared in an adjacent room

The US state of Oklahoma has unveiled its remodelled death chamber, where at least three men are scheduled to be executed before the end of the year.

The chamber at the Oklahoma State Penitentiary in McAlester was renovated at a cost of $71,000 (£44,000).

It features more space for the executioners to work and new audio and video equipment.

It was rebuilt after an April execution went awry when executioners failed to inject the lethal drugs properly.

Convicted murderer Clayton Lockett writhed for nearly an hour as the execution team struggled to find suitable veins in his arms, legs, neck and feet.

They ultimately attempted to inject the drugs into a vein in his groin but that failed, dispersing the powerful sedative into his tissue rather than directing it into his bloodstream.

The execution was halted when the error was discovered. Lockett died shortly after of a heart attack.

Image copyright AP Image caption The actual execution room was slightly shortened to make room for the chemical team in the adjacent room

On Thursday, Oklahoma corrections officials took news media on a tour of the new facility, showing the enlarged "chemical room" where the executioners administer the lethal drugs.

By expanding the "chemical room", the state reduced the size of the witness chamber and the room where the condemned is strapped down. In future, five members of the news media will be allowed to witness executions, down from 12.

The chamber has cameras, video screens and a heartbeat monitor enabling the executioners to track the procedure's progress. An ultrasound machine will enable the team to more easily locate the condemned's veins.

Charles Fredrick Warner, who had initially been scheduled to die just hours after Lockett on 20 April, will be next in the chamber, his execution scheduled for 13 November.

Warner was convicted for the 1997 murder and rape of an 11-month-old girl.