President Vladimir Putin's advisor said on Friday that Ukrainian President Viktor Yanukovych would lose power as a result of the ex-Soviet state's political crisis unless he "quashes the rebellion".

"He (Yanukovych) is currently in the situation of a creeping coup and because he is the guarantor of the Constitution, security and integrity of Ukraine, then the president has no choice," Kremlin economic aide Sergei Glazyev said in remarks released on Friday.

"Either he defends Ukrainian statehood and quashes the rebellion provoked by financial and outside forces or he risks losing power, and mounting chaos and an internal conflict, from which no exit can be seen, await Ukraine."

Glazyev spoke in an interview to Russian energy giant Gazprom's corporate magazine. The full text of the interview was published on the blog of the magazine's editor, Sergei Pravosudov, on Friday.

A Kremlin spokeswoman declined comment.

The hawkish aide is often seen as the Kremlin's pointman on Ukraine and has angered officials in Kiev in the past.

Last summer he threatened Ukraine with economic retaliation if it signed key economic and political agreements with the European Union.

In November, Yanukovych scrapped plans to sign an historic EU trade deal under pressure from the Kremlin, sparking huge protests.

On Friday, the Ukrainian defense ministry released a statement urging the president to take "urgent" steps to ease the crisis, weighing in on the turmoil for the first time.

Ukraine is mired in deep economic trouble and has accepted a $15 billion bailout from Moscow. The Russian government has already released the first $3-billion tranche.

Putin this week said that further payments would not be released until a new government is named, indicating that the Kremlin may renege on its promise of the bailout.