Conservationists have launched a last-ditch attempt to track down the slender-billed curlew - Europe's rarest bird.

Conservationists have launched a last-ditch attempt to track down the slender-billed curlew - Europe's rarest bird.

The crow-sized wading bird has not been spotted since 1999, but hopes remain that a few individuals still exist.

The RSPB and other BirdLife International partners hope to confirm the once-common bird has not become extinct and then identify and protect sites where it is still found.

The species used to be seen regularly across Europe, the Middle East and Africa, but numbers declined dramatically in the 20th century and by 1994 the population was estimated at just 50-270 birds.

There is a chance, however, that small numbers of them may have been overlooked and could be wintering in remote parts of North Africa or the Middle East - perhaps in Iraq and Iran, which are relatively inaccessible to expert birdwatchers.

The RSPB's Nicola Crockford said: "Although the situation for the slender-billed curlew does look gloomy, the fact that other species have risen from the dead' recently does fuel our optimism.

"Additionally, this bird was known to inhabit remote areas so it is just possible that small numbers of the bird may still be wintering in an isolated part of North Africa or the Middle East, or that some unknown nesting site may be discovered in the depths of central Asia.

"But our quest is definitely a race against time."

A tool kit to help bird-watchers identify the species can be found on the web at www.slenderbilledcurlew.net.