Hong Kong (CNN) -- Four men convicted of murdering 13 Chinese sailors on the Mekong River in the northern Thai province of Chiang Rai in 2011 were executed in China Friday, state media reported.
Chinese authorities identified one of the men as a Myanmar drug lord named Naw Kham, with the other three -- believed to be members of his gang -- named as Hsang Kham from Thailand, Yi Lai, referred to as "stateless," and Zha Xika, a Laotian, the state-run Xinhua new agency reported.
Xinhua referred to Kham's nickname as "the Godfather," saying that his was "the largest armed drug trafficking gang on the Mekong River."
The four men were executed by lethal injection in the city of Kunming in southwest China's Yunnan Province, the Kunming Intermediate People's Court said, Xinhua said. Their appeal was rejected last month.
Chinese prosecutors defended the decision, saying the case had built up sufficient evidence, and that the actions of the four men were held to be extremely cruel. Prosecutor Zhang Weiting from the People's Procuratorate of Yunnan Province told Xinhua that "intentional murder is the heaviest crime in China and the murderers deserve their sentence."
Thai authorities discovered the gruesome murder scene in October 2011 after boarding two cargo ships that had come under gunfire. They found nearly 1 million amphetamines and 12 dead bodies, some with their hands bound. One sailor was missing.
The gang was arrested in a joint operation by police from China, Laos, Myanmar and Thailand, according to Xinhua. The agency added that the gang colluded with Thai soldiers in the attack on the cargo ships, the Hua Ping and Yu Xing 8.
Kham was also accused of directing several of his subordinates in the kidnapping of Chinese sailors and hijacking of cargo ships in exchange for a ransom in early April 2011, the court said, according to Chinese state media.
In an interview from his prison cell with state broadcaster CCTV Friday, Kham appeared to express regret about his past. "The Golden Triangle area is a place of evil," he said, referring to one of Southeast Asia's main drug-producing areas that overlaps several countries in the region. "It turns good people bad.
"People come here doing business, but they couldn't resist the temptation of drugs, then they become drug dealers too."
After the execution, the court was to hand over their remains, wills and personal belongings to relatives or relevant consulates, Xinhua said.
Two additional gang members received death sentences with reprieves and will serve eight years in jail.
The death penalty remains an iconic form of punishment in China, where executions are used as a public warning. Sentencing is broadcast on state television.
China carries out the most executions by far in the world each year, according to Amnesty International -- thought to number in the thousands -- though it does not provide an exact figure. The official number of executions is a state secret.
However, the group admits Beijing has taken steps in recent years to reduce the number of capital crimes.
In 2011, Amnesty said China abolished the death sentences for 13 non-violent offenses and in cases where the accused was over the age of 75 -- though it warned people were rarely executed in these cases, with the implementation of the death penalty often extended for other capital offenses.
CNN's CY Xu in Beijing contributed to this report.