London Mayor Boris Johnson called for new powers to allow authorities in the capital to cap the number of minicabs after an 18 percent surge since the start of last year.

Johnson will push the U.K. government to pass a new law enabling the capital’s transit authority, Transport for London, to limit growth of the minicab fleet, according to a statement emailed by his office.

There are currently 78,690 minicabs in London, a rise of 12,268 in recent months, it said. Minicabs must be booked in advance, unlike traditional black cabs that can be hailed in the street.

"We must be able to take action against the threat posed by the massive increase we are seeing in the number of private-hire vehicles," Johnson said in the statement. "There are already over 75,000 minicabs and rising. We’re starting to see a threat to free movement of traffic on the roads."

The surge in minicabs risks squeezing out black taxis, whose drivers must memorize 25,000 streets and 20,000 landmarks in order to pass a test known as "The Knowledge" and obtain a license. Black-taxi license applications are down 20 percent so far this year, according to data obtained by Bloomberg from Transport for London.

Johnson will also push for powers to regulate pedicabs and rickshaws, which "jam up roads in the West End and unnecessarily and consistently fail to ensure the safety of their passengers," according to the statement.