MOSCOW (Reuters) - Russian Foreign Minister Sergei Lavrov said on Wednesday that Moscow cannot order pro-Russian armed groups in Ukraine's Crimea region to return to their bases because they are "self-defense" forces, not Russian soldiers.

Western states are discussing a potential resolution to the crisis ignited by Russian intervention in Crimea under which Russia would pull its forces back to their bases on the Black Sea peninsula and allow in international monitors.

But asked if Moscow would order pro-Russian forces wearing fatigues without identification markings back to base, Lavrov told a joint news conference with Spanish Foreign Minister Jose Manuel Garcia-Margallo in Madrid it could not do so.

"If you mean the self-defense units created by residents of Crimea, we give them no orders, they take no orders from us," he told the news conference shown live on Russian state television.

"As for the military personnel of the Black Sea Fleet, they are in their deployment sites," Lavrov said, referring to a Russian naval unit based in Crimea. "Yes, additional vigilance measures were taken to safeguard the sites.

"We will do everything to prevent bloodshed."

He also said it was up to Crimean and Ukrainian authorities to decide whether to grant international monitors access.

Lavrov was speaking ahead of his first face-to-face meeting with U.S. Secretary of State John Kerry since Russia effectively took control of Crimea and reserved the right to invade Ukraine, prompting the United States and European Union to threaten Moscow with sanctions.

Lavrov also reiterated Moscow's calls to honor a February 21 agreement between rival sides in Kiev as the basis for a solution to the crisis.

Moscow's envoy refused to sign the EU-brokered deal at the time.

(Reporting by Gabriela Baczynska, additional reporting by Julien Toyer in Madrid, editing by Steve Gutterman)