MOSCOW/ANKARA (Reuters) - President Tayyip Erdogan said on Friday that Turkey will not stay silent over Russian-backed mercenaries supporting Khalifa Haftar in Libya, as Moscow voiced concerns over possible Turkish military deployment to Libya in support of Haftar’s enemies.

Turkey has backed Libya’s internationally recognized government led by Fayez al-Serraj and the two sides signed a security agreement last month which could deepen military cooperation between them.

Turkey has already sent military supplies to Libya in violation of a United Nations arms embargo, according a report by U.N. experts seen by Reuters last month. It said Serraj’s Government of National Accord (GNA) asked Turkey for help after Haftar received support from Jordan and the United Arab Emirates.

Turkey had not responded directly to the assertions in the report, but Erdogan said Ankara could not ignore the support that Haftar was receiving from the Kremlin-linked Wagner group.

“Through the group named Wagner, they are literally working as Haftar’s mercenaries in Libya. You know who is paying them,” Erdogan was quoted by broadcaster NTV as saying on a flight back from Malaysia.

“That is the case, and it would not be right for us to remain silent against all of this. We have done our best until now, and will continue to do so,” he added.

Erdogan’s comments come a day after Serraj’s government said it ratified last month’s security and military accord with Ankara, opening the way for greater Turkish support, as it fights a months-long offensive by Haftar’s forces.

Earlier on Friday, Russia said it was very concerned by the prospect of Turkey sending troops to Libya, adding that the deal on military cooperation between Ankara and Tripoli raised many questions for Moscow, according to the Interfax news agency.

Erdogan said on Wednesday Turkey would improve cooperation with Libya by offering military support to the GNA and backing joint steps in the eastern Mediterranean. Ankara has previously said it could send military support to the GNA if it requested it, but says no such request has been made yet.

The Kremlin said on Tuesday Erdogan and Russia’s Vladimir Putin would discuss Ankara’s potential military deployment to Libya during talks in Turkey next month.