Bulgaria's restaurant and hotel owners on Monday urged Prime Minister Boyko Borisov to revoke the full smoking ban in indoor spaces, the Sofia News agency reported.

In an open letter to Borisov business representatives said turnover has slumped by an estimated 20 percent to 40 percent since the ban was introduced this past June. They said they were worried about the mass exodus of customers and upcoming bankruptcies in the winter season.

They propose separating facilities as well as space inside restaurants and bars into smoking and non-smoking sections with strict adherence to air-conditioning requirements, and not allowing minors inside smoking places.

The proposal also includes incentives, such as tax deductions, for those who implement the full ban voluntarily.

Hotel and restaurant owners say if the ban is to stay the national budget will lose millions of dollars from taxes, and warn that bankruptcies will lead to higher unemployment, particularly among young people.