A senior adviser to Turkish Prime Minister Recep Tayyip Erdogan said on Sunday that classified documents published Saturday by the Al-Arabiya network were fake.

The documents allege that Turkish pilots killed in Syria after Syrian forces shot down their plane were deliberately executed following consultation between Damascus and Moscow.

“It is crystal clear that the documents published by Al-Arabiya are fake,” wrote Erodgan’s advisor, Ibrahim Kalin, on his Twitter account. He added that “it is well known that intelligence documents do not look like this.”

The plane’s pilots were believed to have been killed instantly, but according to the report the two survived, after their jet was shot down, and were taken into custody by the Syrian Air Force. A letter, allegedly sent by Syrian President Bashar Assad’s office to a top commander, states that the pilots were captured “after their jet was shot down in coordination with the Russian naval base in Tartus.”

Russian military involvement in the shooting down of the plane was suspected for some time.

A subsequent file, also alleged to have been sent by Assad’s office, says, “Based on information and guidance from the Russian leadership comes a need to eliminate the two Turkish pilots detained by the Special Operations Unit in a natural way and their bodies need to be returned to the crash site in international waters.”

In July, Turkey found the bodies of the two pilots and the plane wreckage in the Mediterranean Sea.

The second letter printed by Al-Arabiya suggests that the Assad regime apologize, while at the same time threatening the Turkish government with Syria’s ability to mobilize Kurdish forces on its border. Assad did apologize for the incident in early July, saying his forces had thought the plane was Israeli.