A Tasmanian devil has been killed in a US zoo by an unknown attacker who struck it on the head with a block of asphalt.

Jasper, a four-year-old male, was shipped to Albuquerque BioPark Zoo from the Healesville Sanctuary in Victoria last December.

It was one of four devils at the Albuquerque, New Mexico zoo, which was hoping to establish a breeding program to help save the endangered species.

Zoo staff found Jasper's body on Wednesday US time but did not initially suspect foul play.

"The first suspicion of how the devil died was that it was possibly killed by another devil," the police report states.

"After the necropsy was completed the veterinarian [Ralph] Zimmerman found a small piece of the devil's skull fractured, staff went back into the enclosure."

They then discovered two large chunks of asphalt in the pen.

The police reports suggested someone may have entered a roped-off area to attack Jasper.

Albuquerque zoo had hopes for breeding program

Albuquerque mayor's chief-of-staff, Gilbert Montano said the city was extremely upset by the death.

"It looks like there was malicious intent and essentially our poor Tasmanian devil was killed, intentionally, by what seems to be blunt force trauma to the head," he told KRQE-TV.

Security cameras did not cover the devils' enclosure but footage showed two boys and an adult male leaving the area on Tuesday afternoon.

It was not clear whether Jasper's death would jeopardise the Albuquerque zoo's hopes for a breeding program.

Staff at Healesville Sanctuary, where Jasper was born in 2010, said they were saddened and shocked by his death.

An independent investigator had been assigned to help police with the case.

Anyone convicted of the offence faced up to 18 months in jail.

The BioPark zoo and San Diego Zoo are the only zoos in the US that house Tasmanian devils in the hope of engaging Americans in the animal's plight.