He was seen as the brutal cohort of Ne Win and the man responsible for the ruthless suppression of dissent, notably antigovernment protests in 1962 in which scores of university students were slaughtered.

After serving as chief of the Mandalay and Irrawaddy division army commands, he was brought to the Burmese capital of Rangoon as joint general secretary of the party in 1981.

Sein Lwin, as commander of the security force riot police (Lon Htein) was again responsible for dealing with student protests during the 1988 pro-democracy demonstrations.

Following the military takeover, the junta provided assistance to Sein Lwin, including guards, a pension, several four-wheel drive vehicles and monthly food rations.

Sein Lwin launched his career as leader of Burma with accusations that the country's problems were the fault of individuals, and not the ruling party.

Sein Lwin died on 9 April 2004 at Yangon General Hospital at the age of 80 after his return from Singapore where had sought treatment for a stomach ailment.