NFL commissioner Roger Goodell has claimed that the league couldn't have obtained the video that showed former Baltimore Ravens running back Ray Rice striking his wife.

Rice was cut by the Ravens and indefinitely suspended by the NFL after CCTV footage was released of the 27-year-old punching his then-fiancee in the lift of an Atlantic City hotel.

Goodell, who suspended Rice for two games in the initial aftermath of the incident, has admitted that due to the investigation into the matter the league were not able to obtain the information from the proper channels.

He wrote in a memo to all 32 NFL owners, which was published on NFL.com: "Understanding of New Jersey law is that the casino is prohibited from turning over material to a third party during a law enforcement proceeding, and that doing so would have subjected individuals to prosecution for interference with a criminal investigation.

"Moreover, our longstanding policy in matters like this — where there is a criminal investigation being directed by law enforcement and prosecutors – is to cooperate with law enforcement and take no action to interfere with the criminal justice system.

"In addition, in the context of an ongoing criminal investigation, information obtained outside of law enforcement that has not been tested by prosecutors or by the court system is not necessarily a reliable basis for imposing league discipline."

The Ravens also confirmed that they had not seen the footage until it was released by TMZ on Monday.