Pueblo Democrat Rep. Buffie McFayden and union officials Tuesday called upon the federal government to fully staff the Supermax prison in Florence, saying employee levels are dangerously low.

Staffing at the Supermax, which has been the scene of disturbances this year involving 60 inmates, has dropped to the point that many shifts and posts are not being covered, said union representatives for federal correction officers during a news conference at the Capitol.

Units that house some of the nation's most notorious terrorist go unsupervised for up to 24 hours in some cases, said McFayden and Mike Schnobrich, president of the prison council with the American Federation of Government Employees.

"It's my understanding that whole housing units have gone unstaffed for eight hours or longer, including the terrorist unit," said McFayden. "I'm calling on President Bush and the Congress to personally take note what's happening at Supermax.

"The problem is causing tensions between correctional officers and inmates. We need to protect our employees and our communities here in Colorado."

Union officials claim staffing levels have dropped from 92 percent at the facility to 75 percent.

The charge comes six months after outgoing U.S. Attorney General Roberto Gonzales toured Supermax in February amid security concerns.

Felicia Ponce, a spokeswoman for the Bureau of Prisons, said she could not discuss staffing levels or shift coverage at the prison.

"All of our institutions are staffed at levels that allow us to ensure safety and orderly operations," she said. "Over the past year, we have increased staff."

The Bureau of Prisons added 18 security employees to Supermax in December.

Schnobrich said the prison should have 230 correction officers. In the past six months, staffing has fluctuated between 180 and 200.

Union officials said the prison isn't covering shifts and posts when officers are out sick, on medical leave or on vacation. That means some prisoners are not being let out of their cells one hour per day to exercise. The facility is on a 23-hour lockdown.

"This isn't a new situation. It's a repeated situation," said Schnobrich.

Supermax's 475 inmates are considered the most dangerous in the nation's federal prison system. They include a roster of international and domestic terrorists, including Sept. 11 conspirator Zacarias Mouassaoui and Unabomber Ted Kaczynski.

In January, fights broke out at Supermax, forcing the Bureau of Prisons to shift additional correction officers from other federal prisons to Supermax in Florence to help bring inmates under control.