Turkish Airlines allegedly shipped weapons to unknown groups in Nigeria, which has been ravaged by violence between the army and Boko Haram militants, a new incriminating phone call revealed on Tuesday.

The leaked conversation is the latest blow to Prime Minister Recep Tayyip Erdogan, who has been hit by a corruption probe ensnaring his key allies and a widening phone-tapping scandal.

In a tape posted on YouTube, Mehmet Karatas, an assistant executive of the airline, allegedly tells Mustafa Varank, an advisor to Erdogan, that he feels guilty over national flag carrier’s arms shipment to Nigeria.