"Bulgaria completed the transportation to Greece of 190,570 landmines from the plant near Gorni Lom," the foreign ministry said in a statement.

Greece had contracted a private Bulgarian firm to destroy a total of 1.5 million landmines at the plant, but an explosion ripped through the factory on October 1, 2014, killing 15 people.

The privately-owned plant was then stripped of its licence to decommission the remaining landmines.

With worried local residents long pressing for the removal of the mines, Sofia and Athens have been negotiating their safe transfer back to Greece.

Bulgaria's arms industry, which flourished during communism, was largely privatised in the 1990s.

But many of the new owners had neither the necessary know-how nor the financial means to invest in safety and accidents, sometimes deadly, were frequent.

At the plant in Gorni Lom itself, six workers were also injured in explosions in 2007 and 2010.