France and Germany have demanded that Bulgaria's General Labor Inspectorate apply tighter control on Bulgarian employees sent on business trips by their companies, a minister has warned.

Bulgarian Deputy PM and Labor Minister Ivaylo Kalfin explained on Wednesday that authorities in Paris and Berlin had requested the step amid fears that "social dumping" might be practiced by such employees.

Kalfin told the Bulgarian National Radio that Sofia would take part in an initiative aimed at fighting the grey economy across the EU by sealing partnerships among labor inspectorates of member states.

"What Bulgaria is supporting very vehemently is that a [single] platform should be created to fight undeclared income and employment in the underground economy and it should be accessible for all member states," Kalfin added.

Last year, a EU commissioner voiced concern with Bulgaria's share of grey economy during his visit to the country.

But officials from across the bloc admit that shadow labor activities are also taking a toll on their national GDPs and on Europe's output in general.

The minister was adamant that his government would fight fiercely with employers who do not offer labor contracts to their workers. This follows an incident earlier this April which claimed the lives of four workers buried under the rubble of a hotel near the Black Sea city of Varna. Veronika Hotel collapsed trapping workers who were instructed to demolish it and who did not have proper contracts.