The top U.N. envoy in Afghanistan says recent reports indicate the Islamic State group has established a foothold in Afghanistan, a view echoed by Russia which urged the Security Council to stop the extremists' expansion.

Nicholas Haysom told the council Monday the U.N. mission's assessment is that the Islamic State hasn't stuck "firm roots" in Afghanistan, but it has the potential "to offer an alternative flagpole to which otherwise isolated insurgent splinter groups can rally."

Russia's Deputy U.N. Ambassador Vladimir Safronkov said Moscow is worried about the rise of the terrorist threat in Afghanistan, especially in the formerly quiet north bordering countries that are its friends and allies.

At Monday's meeting, the Security Council voted unanimously to extend the mandate of the U.N. mission in Afghanistan until March 17, 2016.