An extremely rare black flamingo was spotted on 8 April on the Mediterranean island of Cyprus, exciting nature lovers who said it may be the only bird of its type ever observed.

The flamingo, seen feeding on the banks of a salt lake is thought to have a genetic condition known as melanism, which causes it to generate more of the pigment melanin, turning it dark, rather than the usual pink colour.

"Early this morning when we set up the fieldscopes to count the flamingos, we were faced with a big, a really big surprise - there was a black-coloured flamingo among the bigger group," said Pantelis Charilaou, head of the environmental department of the British Sovereign Bases, territory under the control of former colonial power where the bird was seen.

"A melanistic individual is a very rare sighting," Charilaou said, adding that: "A melanistic individual is a genetic anomaly, basically, it's the opposite of an albino, and it is a case when the individual produces more melanin than normal."

The sighting in Cyprus happened during a flamingo count at a sprawling salt lake at the Akrotiri environmental centre on the southern coast of Cyprus. Experts said it may be the same one that was spotted in Israel in 2014.

"From what we've seen on Internet, there was only one sighting a few years ago at Israel, so maybe this is the second one," said Charilaou.

Up to 20,000 greater flamingos descend on Akrotiri salt lake each year.