The official Xinhua News Agency did not explain the jump in death toll from an early report of 13 but said an ad-hoc investigation team convened Thursday when it revealed the latest death toll.
The news report came after China concluded its annual meeting of its ceremonial congress in Beijing, raising questions if the information was kept under wraps to avoid disruption to the convention.
Xinhua says a coal truck and a vehicle carrying liquid methanol collided inside the tunnel in Shaanxi province on March 1, causing a blast and setting fire to more coal trucks.