KYIV, Sept 29 (Reuters) - Ukraine marked Friday's 82nd anniversary of a mass killing, mainly of Jews, in Nazi-occupied Kyiv with an appeal not to forget an event that it said provided the moral basis for opposition to "Russian aggression."

Nazi forces shot dead nearly 34,000 Jewish men, women and children on Sept. 29-30, 1941 at Babyn Yar (also called Babi Yar), a ravine on the outskirts of Kyiv, after occupying the Ukrainian capital - which was then part of the Soviet Union - during World War Two.

Over the next two years, many more people were killed at Babyn Yar. Most were Jews but the victims also included Roma and non-Jewish Ukrainians, Poles and Russians.

"It is very important to always remember history, not to forget. Because 'Never again!' are not empty words," President Volodymyr Zelenskyy said after leaving a candle at a monument of a Jewish menorah erected at the site to honor the victims.

He spoke with a small group of people gathered at the monument including relatives and descendants of the victims and rabbis from Ukrainian cities.

"All our days of commemoration have been made more emotional by the war. It has sharpened our feelings, opened up our wounds. We have become more sensitive to justice, to pain, to memory, to love," said a serviceman called Yurii with the call sign "Seff" as he took part in an annual march to monument.

The Ukrainian foreign ministry urged the world to prevent such killings happening again and drew attention to Russia's invasion of Ukraine 19 months ago.

"The memory of Babyn Yar and the slogan 'Never again' are the moral basis of humanism and opposition to any forms of aggressive-chauvinistic ideologies, in particular, Russian aggression against Ukraine," it said in a statement.

Zelenskyy is Ukraine's first ethnically Jewish president, although he is not publicly religious. Most of his grandfather's family was killed during World War Two.

Russia launched a full-scale invasion on Ukraine in February 2022, saying the goal of the "special military operation" was to de-nazify and demilitarize its neighbor. Kyiv and its Western allies have accused Russia of an unprovoked land grab.

(Reporting by Anna Pruchnicka and Stefaniia Bern, Editing by Timothy Heritage and Philippa Fletcher)