BRUSSELS Fewer than a third of unaccompanied children succeeded in winning asylum in Greece last year, with the rest of the applications rejected or in limbo, aid agency Save the Children said in calling for better protection of those most vulnerable.

Greece is one of the main routes into the European Union for refugees and migrants from the Middle East, Asia and Africa. Hundreds of migrants died off the Greek shores last month when an overcrowded smugglers' boat capsized and sank.

In a report on Thursday, Save the Children said that 981 out of 3,175 asylum requests logged in Greece last year by unaccompanied children - up to 18 years old - were accepted.

"These figures suggest many lone children on the move were denied the right to protection and left without the legal documentation needed to enable them to remain in the country," said the non-governmental organisation (NGO).

It blamed bureaucracy for leaving such minors to live in Greece unofficially and without any documentation, a situation making their already fraught fate even more precarious by increasing the risk of violence, abuse and exploitation.

"Undocumented children live in a state of insecurity and fear of deportation. This fear is particularly sharp for children who are mistakenly registered as adults," Save the Children said.

It called for "a special residence permit for unaccompanied children" who lose their asylum bid, better access to mental health and other medical services, as well as education for what is one of the most vulnerable group of refugees and migrants.

(Reporting by Gabriela Baczynska; editing by Mark Heinrich)