Al-Jazeera has announced that its US news channel Al Jazeera America (AJAM) is to shut down by April - less than three years after it was launched.

AJAM CEO Al Anstey made the announcement in a memo to staff, saying the decision was “driven by the fact that our business model is simply not sustainable in light of the economic challenges in the US media marketplace.”

Operations will cease by April 30th, but Mr Anstey said, "we will continue to show America why AJAM has won respect and the fierce loyalty of so many of our viewers".

In a statement, Al-Jazeera Media Network announced the closure will be accompanied by an expansion of its worldwide digital services into the US, which "will allow US and non-US consumers alike to access the Network’s journalism and content wherever and whenever they want".

The station has consistently struggled for ratings since its launch, with the New York Times reporting its prime-time ratings sometimes struggled "to exceed 30,000 viewers".

AJAM also faced a number of high-profile resignations and lawsuits. One lawsuit included allegations of mistreatment of employees and a claim that the channel had abandoned its objectivity to advance "a pro-Arabic/Middle Eastern agenda, often at the expense of Jewish people."

However, the station has also picked up a number of notable journalistic and broadcasting awards during its short run.

Last month the channel was at the centre of controversy after NFL star Peyton Manning said he will "probably" sue the network after a documentary released by Al-Jazeera's investigative division claimed the athlete was involved in a doping ring with various other professional athletes. Mr Manning has said the report was "totally made up".