South Korea Monday announced tougher rules to combat Internet gaming addiction including a "fatigue system" encouraging players to switch off.

The announcement follows deaths blamed on the addiction, including the case of a couple accused of letting their baby daughter starve while they raised a "virtual" child on the Internet.

The culture ministry said three major game operators would have to introduce a "shutdown" programme from September. Younger users will be limited to a time period set by a parent or guardian.

The firms would also have to restrict access by teenagers at night by using a "fatigue system", which makes games harder as time goes by so that the player becomes bored, it said in a statement.

Currently only four games use the fatigue system but a total of 15 games will have it by the end of this year, it said.

Official data estimates the highly-wired nation has two million web addicts, or 8.8 percent of total online users.

The couple in the baby death case are currently on trial for negligent homicide.

Police have alleged they "raised" an online girl game character while leaving their own prematurely born daughter at home, feeding her just once a day between 12-hour stretches at an Internet cafe.

In March a 32-year-old man died after reportedly playing for five days with few breaks. A similar incident was reported involving a 28-year-old man in 2005.