Japan Airlines said on Thursday it had been reprimanded by the government after one of its pilots took a medicine prohibited for use when flying planes, the latest in a series of safety mishaps that have plagued the country's biggest carrier.

JAL said the pilot flew seven domestic flights in three days while taking a medicine that was prohibited for use when operating a plane.

The company said the pilot, who had had surgery to remove a tumor on the parotid gland near his ear, had returned to work without having been examined by a physician to ensure that he was in good enough condition to fly under industry regulations.

The company said it would take the warning seriously and would report improvement measures to the Ministry of Land, Infrastructure and Transport by July 28.

JAL has been losing passengers to rival All Nippon Airways due to a series of mishaps, including a wheel falling off and an engine catching fire, while management infighting has also weakened its brand image.

The airline was also criticized for announcing a new share issue plan that will lead to a huge dilution of the value of shareholders' stakes just two days after a shareholders' meeting at which no mention was made of the plan.