UN Secretary General Ban Ki-moon has offered condolences to Turkish President Recep Tayyip Erdogan over Saturday's twin bombings in capital Ankara that killed 97 people, sources at the Turkish presidency said Monday.

In a phone conversation with Erdogan, Ban expressed his regrets over the terrorist attack and strongly condemned it.

Erdogan thanked the secretary-general for the solidarity and condolence messages. He added that Turkey was steadfastly struggling against all terrorist organizations, including the PKK, DHKP-C and ISIL.

At least 97 people were killed and more than 240 people were injured in Saturday's twin bombings in front of Ankara’s main train station, according to Turkish Prime Ministry. Three days of mourning for the victims were declared across Turkey early Saturday.

The bombings came about three weeks ahead of Turkey’s Nov. 1 early general elections.

Ban also expressed his concerns over Russia's violation of Turkey's airspace.

A Russian jet violated Turkish air space on its border with Syria on October 5. Moscow indicated that its fighter jet violated Turkish air space due to "bad weather conditions".

Moreover, Ban thanked to Erdogan for Turkey's efforts to settle the dispute between the warring sides in Libya.