The number of migrants detained while trying to cross into Bulgaria our leave it increased by one-fifth in May, the Interior Ministry says.
Statistics released by the ministry show a surge in numbers of people detained on the border between Bulgaria and Turkey, inside the country, or on the frontier betweeen Bulgaria and Serbia.
Police apprehended in May 169 migrants as they were entering the country, only 34 of them on the border with Greece.
As many as 5000 tried to cross in the first 5 months of this year, most of them saying they wer from Iraq or Afghanistan, followed by those from Syria.
In the last week of May alone, 260 were detained on the border between Bulgaria and Serbia, compared to 150 in the previous one.
This comes amid foreign media reports suggesting a "Bulgarian" smuggling route is being opened up following the closure of the so-called "Western Balkans route".