Ukraine said Friday it is investigating several doctors in the western region of Lviv for taking bribes to illegally issue medical documents to men trying to evade military service.

Kyiv has been cracking down on draft dodgers and trying to bolster the ranks of its military, which has been ceding ground in the east due to manpower and ammunition shortages.

Investigators said a ring leader and four doctors were part of an "organised criminal group" that gave formal disability status to patients in exchange for money.

The suspects could lose their legal right to work and face 10 years in jail on bribery charges, the State Bureau of Investigation said in a statement Friday.

The bribes depended on the profile of the patient, the statement said, adding that the most expensive ones were those that allowed men aged for military service to travel abroad.

Ukrainian men between the ages of 18 and 60 have been barred from leaving the country since Russia invaded in February 2022. There are some exceptions, including for those with disabilities.

Ukraine's border service has said it has prevented thousands of men from trying to leave the country illegally.

This month, the government toughened penalties on draft dodgers and obliged men to keep their military registration details with the authorities up to date.