The German city of Cologne is resorting to a "sex tax" on brothels to boost its revenues after national reforms left local authorities short of cash.

City authorities have confirmed they are extending the existing "pleasure tax" already levied on casinos and amusement arcades, to brothels, erotic massage parlours and table-dancing clubs.

Cologne expects to triple its pleasure tax revenues, Inge Schuermann, a city spokeswoman said.

"This is about making taxes fair but also because we are more than up to our necks in financial problems," she said, shortly after Germany's Parliament approved the country's biggest welfare shake-up in decades