In a social media post, Mr. Guterres said he was "horrified" by the incident.

"My heart is with the Jewish community worldwide on this first day of Hannukah, a festival celebrating the miracle of peace and light vanquishing darkness," he wrote.

At least 11 people were killed when two gunmen opened fire on the Hanukkah celebration on Bondi Beach in Sydney, which authorities have called a terrorist attack.

Two of the victims were police officers, according to media reports. One of the gunmen was killed and the other was taken into custody.Against antisemitism

The Secretary-General expressed solidarity with the people and Government of Australia, and with the Jewish community in the country and worldwide, UN Deputy Spokesperson Farhan Haq said in a statement issued later on Sunday.

He "unequivocally condemns antisemitism in all its forms and reiterates that attacks on religious communities and peaceful celebrations strike at the core values of tolerance, coexistence and human dignity," it said.Alliance for understanding

The Secretary-General was in Riyadh, Saudi Arabia, on Sunday, where he addressed the opening of the 11th World Forum of the United Nations Alliance of Civilizations (UNAOC).

The initiative was established 20 years ago to promote respect and understanding between cultures and religions.

In a post on social media, UNAOC High Representative Miguel Angel Moratinos said he was "appalled" at the attack and added his voice to the condemnation.

"I extend my deepest condolences to the families of the victims and wish a speedy recovery to those injured," he said in a tweet.About Hannukah

Hannukah, also spelled Chanukah, is the Jewish festival of lights.

It celebrates the Jewish people regaining the freedom to practice their religion more than 2,000 years ago in a battle against Seleucid (Syrian-Greek) rule.

The eight-day celebration is marked by lighting candles each night on a stand called a menorah which is placed in windows or interior doorways.