Paris (AFP) - French President Francois Hollande said Monday that biting Western sanctions against Russia should be lifted if progress were made in resolving the Ukraine crisis.

"I think the sanctions must stop now. They must be lifted if there is progress. If there is no progress the sanctions will remain," he said during a wide-ranging two-hour interview with France Inter radio station.

He said he was expecting such progress at international talks in Kazakhstan on January 15 in a new push for peace, where Ukraine's Western-backed leader Petro Poroshenko is to meet Russia's Vladimir Putin.

German Chancellor Angela Merkel will also attend the meeting in Astana.

"I am going to Astana on January 15 on one condition, that there be fresh progress. And I think there will be. If it is to meet and talk without making headway, it is not worth it," said Hollande.

The French president said while Europe should keep lines of communication open with Putin, "he must know where to stop, and it has been costly for him."

Sanctions imposed by the European Union and the United States, along with plunging oil prices, have sent the ruble crashing by some 40 percent against the dollar last year.

The punitive measures were slapped on Ukraine's former Soviet master after Moscow annexed Crimea, and was subsequently accused of stoking separatist conflict in the east of the country.

- 'No rollback' until progress -

Washington is not participating in the January 15 talks but said that taking any opportunity to move towards a peaceful resolution of the Ukraine crisis was "positive."

But State Department spokeswoman Jen Psaki warned on the sanctions that "there can be no rollback until there is tangible progress on the ground."

Moscow denies it has backed the conflict which has left over 4,700 dead, as well as a charge it has supplied weapons and troops to the rebel camp.

"Mr Putin does not want to annex eastern Ukraine. He has told me that," said Hollande, who has spoken several times with the Russian leader.

"What he wants is to remain influential. What he wants is for Ukraine not to fall into the NATO camp," said Hollande.

"What we want is that he respects the territorial integrity of Ukraine. What we want is that he does not support the separatists."

- Warships in limbo -

The crisis in Ukraine has prevented cash-strapped France from completing the delivery of two "Mistral-class" warships to Russia, which has been in limbo since hostilities broke out in eastern Ukraine.

In November, Paris pushed back the delivery of the high-tech vessels "until further notice" and just before Christmas celebrations, some 400 sailors training to operate the ships left for Russia.

France, already struggling economically, could be liable for hefty fines if it breaches the 1.2-billion-euro ($1.5-billion) contract.

But it would also risk the wrath of its allies around the world if it were to deliver the hot-button technology to Russia at a time when Moscow is in the diplomatic deep-freeze over the Ukraine unrest.