Israeli Prime Minister Benjamin Netanyahu visited Russia Wednesday to voice concern about Iran's efforts to expand its foothold in Syria.

Netanyahu said at the start of his talks with President Vladimir Putin in Russia's Black Sea resort of Sochi that the growing Iranian presence in Syria threatens Israel and others.

"Iran is making an escalated effort to base itself militarily in Syria," Netanyahu said. "That presents a danger to Israel, the Middle East and in my estimation, the entire world. Iran is already in advance stages of the taking over process of Iraq and Yemen, and in practice already controls Lebanon."

Russia and Iran back Syrian President Bashar Assad in the country's civil war, and have helped his army win back key areas. Moscow has also maintained friendly ties with Israel and established military-to-military contacts to prevent confrontations in Syria.

"We are all in the immense international effort defeating Daesh (the Islamic State group) and that is a welcome thing, but what is not welcome is that Iran enters the areas which Daesh leaves," the Israeli leader said.

"We don't forget for a moment that Iran continues every day to threaten Israel with destruction," Netanyahu said, adding that "we will defend ourselves with all means against this threat."

Israel was opposed to the 2015 nuclear deal Iran reached with world powers, and has long objected to Iran's support for militant groups across the region, including Lebanon's Hezbollah, which went to war with Israel in 2006.

Putin hailed what he described as an "efficient mechanism of cooperation" between Russia and Israel, but did not mention Iran in comments at the start of the talks.