Ukraine must enact promised reforms and root out corruption or risk losing the support of the International Monetary Fund, IMF chief Christine Lagarde said on Wednesday.

The warning follows the shock resignation last week of economy minister, Aivaras Abromavicius, which highlighted deep divisions within the ruling coalition and the patchy performance of Ukraine's reform drive under the $17.5 billion IMF programme.

In a statement, Lagarde said she was concerned about Ukraine's slow progress in tackling graft and reducing the influence of vested interests in policymaking.

"Ukraine risks a return to the pattern of failed economic policies that has plagued its recent history. It is vital that Ukraine's leadership acts now to put the country back on a promising path of reform."

Ukraine has been waiting since October for the IMF to dispense a third tranche of loans, worth $1.7 billion, but slow or delayed reforms and political squabbles have delayed its disbursement.