Two leading US news channels have admitted that they allowed psychological operations officers from the military to work as placement interns at their headquarters during the Kosovo war.

Cable Network News (CNN) and National Public Radio, (NPR) denied that the "psy-ops" officers influenced news coverage and said the internships had been stopped as soon as senior managers found out . For its part, the army said the programme was only intended to give young army media specialists some experience of how the news industry functioned.

The interns were restricted to mainly menial tasks such as answering phones, but the fact that military propaganda experts were even present in newsrooms as reports from the Kosovo conflict were being broadcast has triggered a storm of criticism and raised questions about the independence of these networks.

"Maybe CNN was the target of a psy-ops penetration and is still too naive to figure out what was going on," wrote Alexander Cockburn, a liberal newspaper commentator. "In the Kosovo conflict, as with other recent wars, CNN's screen was filled with an unending procession of bellicose advocates of bombing, many of them retired US generals."

CNN hosted five psy-ops officers as temporary, unpaid workers last year, while NPR took three, all from the army's 4th Psychological Operations Group, based at Fort Bragg, North Carolina. The army's psychological operations are prohibited by law from manipulating the US media.

After the existence of the CNN internship programme was published in the Dutch newspaper, Trouw, the network immediately cancelled it.

Susan Binford, the head of CNN public relations said: "Is the whole thing embarrassing? Yes. Did it compromise us journalistically? No."

However, the independent watchdog group, Fairness & Accuracy in Reporting asked in a press release: "Even if the psy-ops officers working in the newsroom did not influence news reporting, did the network allow the military to conduct an intelligence-gathering mission against CNN itself?"