Tokyo  - Japan on Thursday executed four convicted murderers, the Justice Ministry announced, a decision expected to draw renewed protests from pressure groups.

Japan is one of the very few industrialized countries upholding capital punishment. The world's second largest economy after the United States faces regular international condemnation from human rights organizations like Amnesty International over prison conditions and its continued adherence to capital punishment.

Relatives are informed of executions only after the fact, and prisoners of death row are told of their upcoming death only in morning of their executions, leaving them only hours to live.

In 2008, the country executed 15 prisoners, a sharp increase from 2007, when nine condemned prisoners were hanged, the usual method of execution in Japan.

The four condemned prisoners were executed in prisons in Tokyo, Nagoya and Fukuoka. (dpa)