German employers have rejected a union call to increase the country's minimum wage just one year after it was introduced.

Raising the minimum wage from 8.50 euros (9.30 dollars) an hour was "absolutely incomprehensible and not realistic," German Employers' Federation Ingo Kramer told dpa on Wednesday.

Frank Bsirske, who heads up Germany's service sector union Verdi, called in September for an increase to 10 euros.

The WSI economic institute, which has close ties to the union movement, has suggested 9 euros would be a more appropriate level for the minimum wage, which came into force on January 1 this year.

Labour unions expect recent higher pay settlements for the general workforce will result in the government's minimum wage commission recommending in the middle of next year raising the minimum wage as part of a review.

The unions see the adjustment as taking place in 2017.

Instead of an increase, German business has been arguing for cutting the minimum wage to help integrate into the workforce the large numbers of refugees that have arrived in Germany this year.