Authorities in Berlin are planning to crack down on private vacation apartment rentals, citing a shortage of affordable housing in the German capital.

Local lawmakers voted to pass a bill Thursday requiring anyone who rents out a private apartment for short periods of time to obtain official permission.

The move could affect an estimated 15,000 apartments in Berlin that are currently being rented to tourists and other short-term visitors.

Center-left lawmaker Iris Spranger says there would be a two-year transition period to help businesses that have specialized in such rentals.

Online apartment booking sites such as Airbnb.com have protested the plan. The site claims visitors who book through its system contribute 100 million euros ($135 million) to the city's economy each year.