The Office of the U.N. High Commissioner for Human Rights has expressed regret over the executions of Aum Shinrikyo founder Shoko Asahara and six other former members of the cult, calling for a national debate on the death penalty.

“We regret that seven people were today executed in Japan,” Ravina Shamdasani, spokeswoman for the U.N. human rights agency, said in a written statement, while extending its sympathy to the victims of crimes committed by Aum, including the 1995 sarin gas attack on the Tokyo subway system.

“Undeniably, it is crucial to deliver justice to the victims of these heinous crimes. But the death penalty only compounds injustice and is no greater deterrent than other forms of punishment,” Shamdasani said.

A fervent advocate of the full abolition of the death penalty, the Geneva-based human rights promotion agency has repeatedly asked the government to establish a moratorium as a first step toward the final abrogation of the punishment.

“This is essential to be able to hold an informed national debate on the use of the punishment,” Shamdasani said, calling on Japanese authorities to increase transparency on the use of the death penalty to promote discussions.

“We will follow up for more information, including on the six other (Aum) inmates on death row in relation to this case,” she added.