Seven members of a Japanese murderous doomsday cult were hanged suddenly last week after more than 20 years on death row.

The group, some of whom met their end in a sterile facility called the Detention House, were sentenced to death for carrying out a deadly gas attack in 1995.

Alongside the US, Japan is one of the few first world countries that still has the death penalty, reports The Sun.

But unlike America Japanese inmates are not afforded the luxury of knowing when they will die. Their end could come at any time.

Often, inmates are told of their fate the morning of the execution, sometimes even just an hour before.

Death drop: The wood-paneled room above, with the blue curtains, is where the condemned prisoner is taken. A rope is tied around their neck and then they are dropped into the grey-tiled clinical room below

The Asian nation does not normally kill more than 10 people each year. From 1977 to 2007 Japan never executed more than nine people in any 12 month period.

But last week it executed seven at various facilities across the nation. This included the leader and six members of Aum Shinrikyo, a cult that released deadly sarin gas into the Tokyo subway killing 13.

Leader Shoko Asahara, 63, founded Aum Shinrikyo cult in 1984, and his mix of Buddhism, Hinduism and Christianity and social disillusionment attracted thousands of followers.

They ran sham computer and health-food businesses and collected donations to amass wealth to buy land and equipment.

They built an arsenal of chemical, biological and conventional weapons to carry out his vision of overthrowing the government to save the world from a doomsday he said was coming, which ended in the deadly 1994 attack.

During his eight years on trial, Asahara rarely spoke and never acknowledged responsibility or apologized.

Asahara died by hanging, where the neck is broken by a rope as the body falls through a trap door.

Viewing gallery: This is the room where the prisoner is hanged. The large glass window in the background is where witnesses can see the execution being carried out. The round metal rings on the wall and floor, right, are to hold the prisoner in place

Execution chamber: The buttons on the left are pressed by the guards at the moment of execution however only one of them actually opens the red-lined trap door seen in the room right. This is so the guards do not know who actually killed the prisoner. Only the blue curtain separates them from the condemned

A ceiling mounted pulley is used for the hanging rope

Final plea: The room where inmates can meet with a priest before they are hanged

Three prison officers simultaneously press buttons to open the trap door so it is not clear who is responsible. This is reduce mental stress.

However inmates are not afforded the same luxury.

The UN Committee against Torture has criticised Japan for the psychological strain the practice of sudden execution places on inmates and their families.

The Justice Ministry in 2007 started releasing the names and crimes of inmates sentenced to death.

Pictures from inside the Detention House show the carpeted floor of the chamber and the hooks on the wall indicate where the inmate is chained.

Executed: Cult leader Shoko Asahara, 63, was executed last week

Last prayers: A golden Buddha statue where handcuffed convicts are blindfolded and led to their death. When the execution order comes, the condemned have just minutes to get their affairs in order before facing the noose

The trap door marked with a red square where an inmate stands, is seen opened at the execution chamber

In the centre is the square trap door, the red lines marks the spot where convicts stand with the noose around their neck, before it opens below them and they plunge to their deaths.

The mechanism is triggered by one of three wall-mounted push buttons in an adjacent room, pressed simultaneously by three officers, although none of them is told which button is the live one that will cause the prisoner's death.

It is similar to the method used when capital punishment is carried out by a firing squad – at least one of which will have a blank cartridge instead of a live round, so it is unknown who fired the fatal shot.

In a stark contrast, the grey-tiled room below, into which the body drops, is cold and clinical.

In another room, a golden Buddha statue stands in an alcove for final prayers before the handcuffed convicts are blindfolded and led to their deaths.

Opposite the execution room is the gallery from where witnesses can view the hanging.

Details on executions had previously been strictly limited and opponents of the death penalty say the ministry still restricts information.