BERLIN (Reuters) - German Foreign Minister Frank-Walter Steinmeier expressed concern on Friday that EU sanctions against Moscow for its actions in Ukraine could destabilize Russia and warned against "turning the screw" any further.

The comments to German weekly Der Spiegel suggest a possible softening in the stance of Steinmeier, a member of the traditionally Russia-friendly Social Democrats (SPD) who has stuck closely to Chancellor Angela Merkel's tough line with Moscow until now.

Steinmeier said the dramatic fall in the rouble currency and falling energy prices had created an economic and financial crisis in Russia, which would affect the political landscape there.

"It cannot be in our interests that this runs out of control," he said. "We need to keep this in mind in our sanctions policy."

Asked if he feared detribalization in Moscow if Europe didn't ease sanctions he said, "I have that concern." He added that the crisis in Russia would only create more uncertainty, and that was why he opposed further penalties.

European Union leaders on Friday warned Moscow they are ready to "stay the course" in a long confrontation if President Vladimir Putin refuses to pull back from Ukraine.

Some in the EU have said they should switch focus away from supporting Ukraine to seeking a detente with Moscow. But leaders voiced their determination to stick together as they have over the past year, while brandishing at Putin the stick of more sanctions and carrot of renewed cooperation.

Germany has taken the lead in trying to convince Putin to engage with the West but to no avail. Steinmeier visited Kiev on Friday seeking to bring new momentum into the peace process.

(Reporting by Alexandra Hudson; Editing by Noah Barkin)