A computer glitch took 50 US nuclear missiles offline for 45 minutes over the weekend but there was no sign of sabotage, a military spokesman said Wednesday.

An initial analysis indicated the problem was caused by a "mechanical failure" with computer hardware, Lieutenant Colonel John Thomas, a spokesman for the Air Force Global Strike Command, told AFP.

The disruption affected a squadron of 50 intercontinental ballistic missiles at F.E. Warren Air Force Base in Wyoming, part of the Global Strike Command that oversees a total of 450 Minutemen III ICBMs in bases located in Western states.

On Tuesday, Air Force experts examining maintenance records discovered that a similar episode occurred at other missile sites more than a decade ago, suggesting there was a recurring problem with certain hardware.

"As of last evening, we got even more fidelity that we're looking at one or two parts" with problems, Thomas said.

"We're focusing on the mechanical issue," he said, but the Air Force so far was not ruling out other causes.

Despite the technical problem in Wyoming, the military retained the ability to launch the weapons in the 319th missile squadron throughout the incident -- if an alert had been issued and commands given, Thomas said.

Immediately after the communications snafu on Saturday, Air Force teams carried out security checks at every missile site in the 319th squadron.

"They found no evidence of tampering to the missiles, to any equipment or defense lines around these sites," Thomas said.

So far there was no sign of sabotage or botched procedures by Air Force missile crews, he added.

"At this time, there's no reason to think from anything we've seen that there was anything intentional or malicious in this fault."

The Air Force has come under pressure in recent years to improve how it manages the country's nuclear arsenal after a series of embarrassing incidents that revealed lax oversight.

As a result, a new military command to oversee the nuclear mission, Global Strike Command, was formed last year and became fully operational this month.

At the 319th squadron in Wyoming, five launch control centers control 10 missiles each. Air Force officers eventually found that the mechanical problem was related to one of the launch centers.

Aside from 450 land-based nuclear missiles, the US military can also deliver nuclear missiles from airplanes or launch them from submarines.

President Barack Obama was briefed about the event Tuesday.