Rights group Amnesty International is calling on the governor of Anambra state, south-eastern Nigeria, to investigate alleged killings of pro-Biafra secessionists. The pro-Biafra movement calls for the independence of territories forcibly annexed to modern-day Nigeria during British colonisation, ended in 1960.

Last year, Amnesty released a report documenting alleged abuses against supporters of the Indigenous People of Biafra (Ipob) movement.

The group claimed security forces killed at least 150 people "and injured hundreds more during peaceful assemblies" since August 2015.

"On 30 May 2016, during the Biafra Remembrance Day, around 1,000 activists gathered for a rally in Onitsha, Anambra state, south east Nigeria. 60 IBOP were killed by security forces that day," Amnesty said.

At the time, an Ipob coordinator who witnessed some of the alleged violence on demonstrators told IBTimes UKsecurity forces used tear gas and fired shots in the air to intimidate people, who ran away.

The army denied the allegations, claiming it intervened to prevent "ethnic clashes" and accused Amnesty of trying to tarnish its image.

But Amnesty has now created a petition urging Anambra's governor, Willie Obiano, "to instruct a prompt, independent and impartial inquiry into the killings of Biafra activists and other serious human rights violations, committed by the security forces."

Obiano's spokesperson has not responded to a request for comments.

A Biafran Republic was established in 1967 but re-annexed to Nigeria in 1970, following a bloody civil war that claimed millions of lives.

Independence calls have gained renewed momentum following the arrest of Nnamdi Kanu, one of the leaders of the movement, in October 2015. Kanu, Ipob leader and director of UK-based Radio Biafra, is standing trial on treasonable felony charges.

The Nigerian government has always maintained the country's unity was a priority and that although peaceful pro-Biafran protests were welcome, demanding the breakaway of the Biafran territories went against the constitution.

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