FACTBOX-Who are the Ukrainian children at the heart of Putin arrest warrant?

KYIV, March 19 (Reuters) – In its arrest warrant for Vladimir Putin, the International Criminal Court accused the Russian president of the war crime of unlawful deportation of people, in particular children, and their unlawful transfer from occupied areas of Ukraine to the Russian Federation.

The ICC issued a separate warrant on the same charge for Maria Alekseyevna Lvova-Belova, the Russian commissioner for children’s rights.

Moscow dismissed Friday’s move, with Kremlin spokesman Dmitry Peskov calling the allegations “outrageous”. Russia, which has denied targeting civilians since its invasion in February last year, has repeatedly denied its forces have committed atrocities, and has rejected past allegations of illegally moving Ukrainians.

Following are some key facts and figures provided by the Ukrainian authorities on the issue: – Daria Herasymchuk, Advisor-Commissioner of the President of Ukraine for Children's Rights and Rehabilitation, described in an interview with Reuters on March 17 five main ways she said Russia has used to illegally transfer Ukrainian children.

They include:

offering families living in occupied areas to take children for holidays in Russian children’s camps and not returning them during an agreed timeframe;

taking Ukrainian children away from care institutions in occupied areas;

separating children from parents at filtration checkpoints – the places where Ukrainian citizens from regions under Russian occupation are checked and processed before being allowed to enter Russia;

taking away parental rights through laws enforced on occupied territories;

taking children away in cases where they were staying with other adults after their parents were killed in the war

– Ukraine’s Prosecutor General Andriy Kostin said on March 17 the prosecutors were investigating cases of deportation of over 16,000 children from Russian-occupied areas of Donetsk, Luhansk, Kharkiv and Kherson regions. “But the real figure can be much higher,” Kostin said on his Facebook page.

– Ukraine has so far managed to return 308 children, officials said.

– Iryna Vereshchuk, minister for reintegration of temporarily occupied territories, issued a public appeal on Saturday to Russian officials asking for lists of all Ukrainian orphans and all Ukrainian children whose parents were stripped of parental rights who are currently in occupied Ukrainian areas or were illegally transferred to Russia.

– A report published in February by the Humanitarian Research Lab at Yale School of Public Health as part of the Conflict Observatory said Russia has held at least 6,000 Ukrainian children – likely many more – in sites in Russian-held Crimea and Russia whose primary purpose appears to be political re-education. The report said Yale University researchers had identified at least 43 camps and other facilities where Ukrainian children have been held that were part of a “large-scale systematic network” operated by Moscow.

(Reporting by Anna Dabrowska and Olena Harmash Editing by Frances Kerry)