Thousands of stateless people are being held in immigration detention centres across Europe even though they cannot be deported because no country recognises them as citizens, the campaigners said.

They urged European governments to introduce procedures for identifying stateless people so they can be protected in the same way as refugees and given a chance to rebuild their lives. 

Francois Crepeau, U.N. special rapporteur on the human rights of migrants, said the immigration detention of stateless people was "one of the silent tragedies of our globalised world".

It is a tragedy that is completely preventable, but due to a lack of will and attention, continues to harm thousands of lives all around the world every year

"It is a tragedy that is completely preventable, but due to a lack of will and attention, continues to harm thousands of lives all around the world every year," he said in a foreword to new guidelines on protecting stateless people from detention.

Chris Nash, director of the European Network on Statelessness (ENS), which produced the guidance, said the detention of stateless people for long periods was an "extremely disturbing trend."

"Across Europe a failure by states to put in place effective systems to identify stateless persons leaves thousands exposed to repeated and lengthy detention," he added.

Campaigners say there are likely to be stateless people among the hundreds of thousands arriving in Europe, as many of the countries they are fleeing, including Syria, Iraq and Afghanistan, have significant stateless populations.