Greece plans to reduce overcrowding at migrant camps on its islands, a government official said on Wednesday, to ease growing tensions and improve conditions that campaigners have called "disgraceful.

More than 10,700 migrants are now sheltered on five Greek islands, which have capacity for 7,450, according to government data. Charity Save the Children said they were living in "dirty, unsafe conditions ... with no end in sight."

Greece now plans to build several new facilities with a capacity of about 1,000 people each, to transfer migrants from the islands and other strained or temporary sites.