SEOUL (Reuters) - An American lost his appeal on Wednesday against a 20-year jail term for the murder of a Korean student stabbed in a burger bar 20 years ago, a case that sparked huge hostility towards U.S. military bases in South Korea.

Arthur John Patterson, 17 at the time of the 1997 murder, and his friend, Edward Lee, also a U.S. citizen, were both suspects in the murder of Cho Joong-pil, 22, at a Burger King restaurant in the Seoul night life district of Itaewon.

The two accused each other of killing Cho.

Lee was sentenced to life in prison and later acquitted due to a lack of evidence. Patterson was charged with destruction of evidence, fled to the United States and was extradited to South Korea in 2011.

A court sentenced Patterson, the son of a contractor to the U.S. Army, to life in prison in January 2016, but as he was under 18 at the time of the killing, the maximum sentence of 20 years was handed down.

Patterson appealed, claiming the statute of limitations and an abuse of power by prosecutors.

Supreme Court Judge Kim Jae-hyung rejected both claims on Wednesday and upheld the 20-year sentence.

The case attracted a new round of attention when a film based on the killing, “The Case of the Itaewon Homicide”, was released in South Korea in 2009.

The U.S. Army presence in South Korea dates back to the end of the 1950-53 Korean War and serves as a deterrent against attack by North Korea.