Bird watchers in Manchester got excited when a flock of blue pigeons was spotted in the city.

But the birds were not quite what they seemed, reports the Daily Express.

They were just ordinary pigeons which turned blue after nesting inside a dye factory.

They set up home in a factory in Collyhurst, Manchester, which makes blue dye for printer cartridges.

Twitcher Diane Ryan was on her way home from work at a sheltered housing scheme close to the factory when she spotted the blue birds

She said: "I just saw these blue pigeons on a patch of ground outside this big Victorian mill.

"When I first saw them I couldn't believe it, there were about four or five of them and since then I've seen quite a few more.

"Then I looked up at the mill and the side of it is covered in blue dye. I realised that the pigeons must have been nesting in the building and had been dyed blue."