The killing of black people, especially those of Nigerian origin in London, was "worrisome and disturbing”, said Abike Dabiri-Erewa, the senior special assistant to Mr Buhari on foreign affairs and the diaspora.

A total of 50 black people, mainly young, are reported to have been stabbed or gunned down in London since January, her office said in a statement.

This included nine Nigerian youth killed in London and other parts of the UK, the statement added.

Ms Dabiri-Erewa had written a protest letter to the UK High Commissioner in Nigeria, demanding an investigation and justice, the statement said.