Lyft Inc. was sued for allegedly refusing to pay $9 million for private arbitration for thousands of drivers who were blocked by the company from pursing claims in court that they are wrongly classified as independent contractors.

About 3,240 drivers want Lyft to spend $2,650 on each individual arbitration as the ride-hailing company heads toward an initial public offering. Larger rival Uber Technologies Inc., which has also announced plans for an IPO, faces similar claims that it left 12,500 drivers in the lurch by not paying for their arbitrations.

Drivers for both companies are bound by their contracts to resolve workplace disputes in arbitration rather than in court.