TOKYO (Reuters) - Japan's biggest lawyers' group on Friday (Oct 7) called for the abolition of the death penalty, a controversial move in country where a large majority of the public supports executing criminals convicted of the most serious offences.

Human rights advocates have long denounced Japan's capital punishment system, under which prisoners are told without warning they will be hanged within hours, but there has been little momentum for change.

Some 80 per cent of the public and the core of Prime Minister Shinzo Abe's ruling party favour capital punishment. Japan and the United States are the only two members of the Group of Seven advanced economies to practise it.

The Japan Federation of Bar Associations issued a declaration calling for the abolishment of the death penalty by 2020, citing the possibility of wrongful convictions and international trends against capital punishment.

It also said there was little evidence that it deterred crime. "There's a serious risk of false charges under Japan's criminal justice system, which has fatal flaws in the disclosure of evidence and long periods of detainment and interrogation," the statement said.

The death penalty is currently used for crimes including murder, coups and arson or rape that causes death.

The move by the lawyers' group was expected to be opposed by a politically vocal victims' rights group, which has consistently urged that the death penalty be maintained.

"When a life is taken by crime, that life will never return," the group said on its homepage. "For the dead person's loved ones to want heavy punishment is only natural."

The danger, said Mr Shizuka Kamei, a former Cabinet member who was a police official for decades before entering politics, was that an innocent person may end up condemned.

"Depriving an innocent, defenceless person of their life is a heinous killing on the part of the nation," Mr Kamei, head of an anti-death penalty lawmakers group, said during a news conference on Thursday.

Proponents of the death penalty say it deters crime, but activists note that nearly 99 per cent of criminal trials in Japan end with convictions and reliance on confessions is high. Suspects are not always guaranteed the presence of a lawyer.

There were 127 people on death row at several prisons around Japan at the end of 2015.