Russian President Vladimir Putin on Thursday gave Ukraine a one-month deadline to settle its debt for gas imports from Russia, warning that after this period Moscow would demand pre-payment from Kiev for gas. "We are prepared to wait one month. If after one month we do not receive any payments then we will switch, in line with the contract, to so-called pre-payment," Putin told a phone-in session. This would raise the spectre of Russia cutting off gas to Ukraine if it does not pay in advance and possible disruption of supplies to Europe.