Major German magazine Der Spiegel has said one of its award-winning journalists has 'falsified articles on a grand scale'.

Reporter and editor Claas Relotius published just under 60 articles for the long-running news magazine since 2011.

He has won multiple high profile awards, including CNN Journalist of the Year in 2014.

However, Der Spiegel claims he has now admitted that at least 14 articles have been "at least in part fabrications".

It apparently came to light after another reporter, Juan Moreno, grew "distrustful" of 33-year-old Mr Relotius while they were working together on a story about a vigilante group patrolling the US-Mexico border.

While reporting on another story, Mr Morena is said to have taken advantage of a trip to the US to gather "incriminating information" about his colleague.

In an article published on their website, Der Spiegel explains: "After initially denying the allegations, Relotius finally confessed at the end of last week.

"It has emerged that he invented entire passages -- not only in the article Hunter's border, but also in a number of other articles."

Reuters reports Relotius has now been fired.

According to the magazine, Mr Relotius included individuals in stories who he had never actually met or spoken to.

He's also accused of making up quotes.

It also says it can't be ruled out that other media outlets were affected, as the reporter had written for various other major German publications.

Relotius' articles for Der Spiegel will remain online with a notification about the development until a full in-house investigation has been carried out into the scope of the apparent falsifications.

Der Spiegel has been operating since the 1940s, and has a distribution of over 700,000 issues every week.