An economic advisor to Ukrainian President Volodymyr Zelenskyy said Tuesday that war-crimes charges would be brought against the leaders of major Western banks.

In an interview with CNBC, the advisor said that Russia is committing war crimes against Ukrainians. Everyone who is financing war criminals who are doing terrible things in Ukranian is committing war crimes.

Ustenko wrote to the CEOs of Citigroup and HSBC asking them to stop doing business with companies that trade Russian oil and sell Russian oil and gas shares.

In an interview with CNBC, Ustenko said that they would pursue managers of the banks.

There are different options. The first choice is the International Criminal Court.

Ustenko said that the banks' activities would be reported to the International Criminal Court.

The power of the International Criminal Court is not limited to prosecuting people.

Ustenko wrote to the bank CEOs accusing them of prolonging the war in Ukraine.

According to the Financial Times, Ustenko said in his letter that the bank's Russian securities investment trust holds shares in several companies. According to the Financial Times, HSBC's asset-management arm has stakes in two Russian companies, as well as Citigroup extending credit to two other Russian companies.

Insider didn't get a response from the banks.

The Financial Times was told by Citigroup that it had stopped doing business in Russia. The publication was told that it helped implement the sanctions.