The Virginia Department of Motor Vehicles sent cease and desist letters to Uber and Lyft on Thursday, saying the ride-sharing service companies are operating illegally.

Uber and Lyft now face fines, according to the letters, which accused them of operating without proper permits and in violation of state law, CNET reported. The state DMV issued civil penalties against the two app-based services in April.

"Uber has been providing Virginians with safe, affordable and reliable transportation options for months and has continued to work in good faith with the DMV to create a regulatory framework for ridesharing," Uber spokesperson Natalia Montalvo said in a response statement quoted by CNET.

"The DMV decision today hurts thousands of small business entrepreneurs who rely on the Uber platform to make a living, create new jobs and contribute to the economy--and it hurts the countless residents who rely on Uber to connect them with affordable, safe and reliable transportation alternatives."

Richard D. Holcomb, commissioner of the Virginia DMV, wrote that the car services should study how their business models work with state laws instead of continuing their "illegal operations," CNET reported.

Uber launched four years ago and is now available in 35 countries, while Lyft has spread to 60 U.S. cities since its start in 2012.

Lyft will continue operations as normal despite the cease and desist letter.

"We've reviewed state transportation codes and believe we are following the applicable rules," Lyft spokesperson Chelsea Wilson told TIME. "We'll continue normal operations as we work to make policy progress."

Uber, which didn't respond to a request for comment from TIME, has faced trouble in London recently as cab drivers fear the service will take away their business. Uber and London transportation authorities say the app doesn't count as a meter and therefore is allowable under law, but critics disagree.

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