(AP) — The Public Service Commission has sent warnings to two ridesharing companies that they need the commission’s permission to offer services in Nebraska.

On Monday the commission issued letters to Lyft and Uber, two San Francisco companies that use smartphone applications to link motorists and people who would pay for rides. Passengers pay through the app and can even tip electronically.

Uber operates in more than 70 cities around the world. Lyft, which is known for pink mustaches on front bumpers, does business in more than 20 U.S. cities.

Commission director Mark Breiner said during a hearing Tuesday that the companies have advertised on Facebook and Craigslist for drivers in Omaha, Lincoln and Columbus. The commission didn’t take any action at the hearing, and company representatives didn’t appear.