11,764 Pakistanis currently jailed or detained abroad: Sartaj Aziz
The minibus was apparently driven by a 16-year-old Bulgarian who did not have a driver's licence. He was among the dead. The bus was on the motorway near Pazardjik, close to the Greek and Turkish borders.
Police said the migrants did not have any identity documents with them but the survivors said they were Afghan and Pakistani nationals.
In recent months, European Union member Bulgaria has seen a fall in the number of illegal migrants crossing from its southeastern border with Turkey, which was almost completely sealed with a razor-wire-topped fence.
More Indian migrants living in Pakistan than US: PEW Research Centre
Most refugees seek to continue their journey to western and northern Europe. Around 3,000 migrants remain stranded in Bulgaria's rundown refugee shelters, according to latest interior ministry data.
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