By Dan Isaacs BBC Nigeria correspondent

A human rights report into the killing in central Nigeria of over 200 unarmed civilians by the army last October has strongly condemned the Nigerian Government for first encouraging, then failing to condemn, the military action.

According to the report, published by Human Rights Watch, the killings in Benue State constituted a clear case of extrajudicial execution.

The military remains a powerful and largely unaccountable force within Nigeria

There is also strong criticism in the report of foreign diplomats who failed to speak out about the events, described as one of the worst human-rights violations since President Olusegun Obasanjo came to power in 1999.

Over a three-day period, soldiers entered a series of towns and villages in Benue State and opened fire on unarmed residents.

Obasanjo stands accused of condoning military excesses

Journalists who arrived on the scene less than 24 hours after the soldiers had left saw scores of bullet-ridden corpses and every single building razed to the ground in towns otherwise deserted by their terrified populations.

The Human Rights Watch report describes the assault as a well-planned military operation carried out in reprisal for the killing of 19 soldiers in the area two weeks earlier, which was attributed to members of the Tiv ethnic group.

The report says that those killed by the military were targeted simply because they belonged to the same group.

In the report, Human Rights Watch says that not only has President Obasanjo and his government appeared to condone the military action, but that an inquiry set up after strong pressure from human rights groups has not even begun its work, many months after the incident.

Silence abroad

Human Rights Watch says foreign governments have remained conspicuously silent on the issue.

It singles out the United States and Britain - the two countries with the strongest economic and political leverage on Nigeria - for failing to speak out publicly.

It also suggests that these countries regard Nigeria as a critical strategic partner in Africa with whom it is important to preserve close diplomatic relations.

The Benue killings were without question an appalling human rights violation.

The failure or inability of the government to take action against those within the army that carried out the attacks is a powerful reminder that, despite handing over power to civilians almost three years ago, the military remains a powerful and largely unaccountable force within Nigeria.