More than 40 countries have agreed to support International Criminal Court investigations into alleged war crimes in Ukraine.

Ministers, senior government officials and ICC Chief Prosecutor Karim Khan met in London on Monday.

Khan noted that the ICC last week issued an arrest warrant for Russian President Vladimir Putin on suspicion of unlawfully deporting and transferring children to Russia from occupied areas of Ukraine.

Russian officials have said the children were transferred to Russia from Ukraine for their own safety and to help them.

Khan said the issuance of warrants for the first time against a leader and senior officials from a permanent UN Security Council member was a sad occasion.

Khan said, "If there is any semblance of truth to the utterances that this is for the sake of children, instead of giving them a foreign passport, return them to the countries of their nationality."

A Ukrainian official called for international support for the ICC to prevent attacks and sexual assaults on civilians.

British Deputy Prime Minister Dominic Raab told reporters that the London meeting raised 4 million pounds, or about 4.9 million dollars, in extra international funding for the ICC as well as offers to send experts to help improve the court's investigative techniques.

Raab stressed the significance of the countries' backing up their words with deeds and coming up with practical support for the ICC's mission.