MOSCOW/UNITED NATIONS - The death toll from Sunday's attacks in southern Russia's Republic of Dagestan has risen to 20, the region's health minister said on Monday.

"As a result of the terrorist attack in the cities of Makhachkala and Derbent on June 23, 46 people were injured," Tatyana Belyaeva said on social media, adding that 20 people had been killed, including law enforcement officers and civilians.

UN Secretary-General Antonio Guterres on Monday condemned "in the strongest terms" the terrorist attacks that occurred in Russia's Republic of Dagestan on Sunday

The shootings occurred on Sunday at two orthodox churches, a synagogue and a traffic police post in the coastal city of Derbent and Dagestan's capital city of Makhachkala, with previous reports indicating that 15 people had been killed and dozens injured.

Monday to Wednesday were declared as days of mourning for the victims of the attacks.

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UN Secretary-General Antonio Guterres on Monday condemned "in the strongest terms" the terrorist attacks that occurred in Russia's Republic of Dagestan on Sunday.

The UN chief "condemns in the strongest terms Sunday's terrorist attacks against Jewish and Christian religious sites and members of the security forces in the Republic of Dagestan of the Russian Federation," Stephane Dujarric, spokesman for the UN secretary-general, said in a statement.

Guterres conveyed his condolences to the bereaved families and the people and the government of Russia, and wished those injured a speedy recovery, Dujarric said.

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Attacks in southern Russia's Republic of Dagestan on Sunday has left at least 20 people dead and 46 others injured, including law enforcement officers and civilians, the region's health minister said on Monday.