Piers Morgan has been accused of delegitimising the movement for racial equality in the US after telling a CNN commentator who tweeted “all black lives matter” that “all lives matter”.

The former Mirror editor faced a backlash after responding to a tweet from Marc Lamont Hill by claiming millions of white lives are also "devalued" and treated "appallingly” across the world.

Morgan said he preferred not to “categorise the value of life according to skin colour” and suggested the statement 'black lives matter' could only serve to cause more division.

Their exchange saw many Twitter users lambast Morgan for apparently misunderstanding the validity of the movement in light of a spate of killings and shootings across the US.

But Morgan was adamant he understood the context, and later tweeted:

The black lives matter movement began as a hashtag in response to the shooting of the unarmed black teenager Trayvon Martin by his neighbour George Zimmerman, who was acquitted on all charges relating to his death.

It later came to symbolise a wider movement against police brutality and the shooting and killing of black citizens, including Michael Brown, whose death at the hands of a white policeman sparked weeks of rioting in Ferguson.

‘Black lives matter’ also appeared on placards in protests over the death of Eric Garner, who suffocated in a police chokehold, and on Confederate monuments across the US after the Charleston shootings.