Vietnam has executed long-time death row prisoner Le Van Manh, a lawyer confirmed on Saturday, despite international pleas to spare his life.

In 2005 Manh was charged with robbery, as well as the rape and murder of a 13-year-old girl in the northern Thanh Hoa province.

The International Commission of Jurists (ICJ) said police obtained a confession through torture that was relied upon to convict him.

Manh later retracted the confession, saying that police had beaten him severely.

The Supreme Court in Hanoi handed down the death penalty at an appeal trial in 2008.

Hanoi lawyer Nguyen Ha Luan, who helped Manh's family petition the Vietnamese president to halt the execution, posted his death certificate on social media on Saturday.

"According to reports and official letters, defendant Le Van Manh was executed... the (execution) notice letter has been sent to the family," he said on Facebook.

The death certificate stated: "Le Van Manh born in 1982. Nationality: Vietnamese. Died at 08:45 on September 22, 2023, at execution house of Hoa Binh provincial police."

His body was buried at Cho Nhang cemetery, the lawyer said, citing official documents sent to Manh's family.

Earlier this week, the diplomatic missions of the European Union, Canada, Norway and the United Kingdom in Vietnam urged authorities to show Manh mercy.

"We strongly oppose the use of capital punishment at all times and in all circumstances, which is a cruel, inhuman and degrading punishment and can never be justified, and advocate for Vietnam to adopt a moratorium on all executions," the joint statement said.

Amnesty International called the execution "sickening." (AFP)