The UK will not be able to impose sanctions on Roman Abramovich and other Russian 'oligarchs' for weeks or months, if at all, because the government has failed to provide reasonable grounds for including businessmen on the sanctions list, The Times reported.

The Foreign Office and the National Crime Agency have failed to prove that there are reasonable grounds to sanction the most prominent oligarchs because they have struggled to tie their finances to the Putin regime. .

The NCA is just one of the agencies involved in providing evidence or information about whether someone should be sanctioned.

This is not only our task, his spokesman said.

British lawmakers are increasingly calling for sanctions against Abramovich, but Prime Minister Boris Johnson said he could not comment on individual cases when asked why the Russian billionaire businessman was not targeted.