The Pentagon has expanded the scope of its investigations into a nude photo sharing scandal by US military personnel after finding evidence that it goes beyond the Marine Corps and includes servicemen from all forces.

After the last week discovery that shook the Marines, the media reported on Friday that male service members from all military branches have long been posting nude photos of their female colleagues online.

According to BBC, those involved in the scheme used an anonymous message board called Anon-IB to either request photographs or post the ones they had obtained, or as they called it “wins.”

"Any wright patt wins? I'll start off with some,” an anonymous user wrote, referring to Wright-Patterson Air Force Base in Ohio.

A Marine official told CBS News that at least a half-dozen similar online groups or sites were still active, sharing military nude photos.

Earlier on Friday, US Defense Secretary James Mattis reacted to the news in a statement, blasting the “lack of respect for the dignity and humanity of fellow members of the Department of Defense.”

Calling those who shared the photos guilty of "egregious violations of the fundamental values" of the military, the Pentagon chief warned that such behaviors would not go unpunished.

“We will not excuse or tolerate such behavior if we are to uphold our values and maintain our ability to defeat the enemy on the battlefield,” he said.

Initially, it was believed that the photos were only posted to a Facebook group called “Marines United,” with around 30,000 followers. More than two dozen of the women whose pictures were released have been identified as Marine officers and enlisted service members.

The photographs, published since January 30 via a Google Drive account, have caused yet another scandal for the US military, underscoring ongoing problems of sexual harassment.

The Naval Criminal Investigative Service launched an investigation into the photos as Google and Facebook blocked the accounts posting the pictures to the group.

Marine Corps commandant Robert Neller denounced the trend in a USA Today article on Thursday, vowing to “fix this problem.”