UNITED NATIONS, Dec. 30 -- UN Secretary-General Ban Ki- moon was appalled by the twin bombings that struck Russia's Volgograd city, which left dozens of people dead, a UN spokesperson said on Monday.

Ban's spokesperson Martin Nesirky recalled at a daily news briefing that the Secretary-General, in a statement issued on Sunday, condemned in the strongest terms the terrorist bombing at a train station in Volgograd, Russian Federation that day.

He added that Ban is equally appalled by Monday's attack in Volgograd, and has expressed his condolences to the families of those who have lost their lives in the Volgograd attacks in the last two days.

At least 10 people were killed and 10 more injured early Monday when a bomb went off in a trolleybus in Volgograd. The attack came one day after a female suicide bomber blew herself up at a railway station in the city, killing 17 people and injuring 45 more.

In a telephone conversation with President Vladimir Putin earlier on Monday, Ban stressed the importance of strong international cooperation to fight terrorism and noted that the perpetrators must be brought to justice.

Putin called for the international community to work together in the fight against terrorism and commended the UN for its important role in coordinating efforts in fighting organized crime and terrorism.

Expressing his gratitude to Ban for his personal condolences which were greatly appreciated by the Russian people, he assured the Secretary-General that Russia would work within the bounds of international law to bring the perpetrators to justice.