BERLIN (REUTERS) - Germany has deployed troops with the EU's peacekeeping mission in Bosnia for the first time in a decade as concerns mount about instability from the Ukraine war spilling over to the Western Balkans.

On Tuesday (Aug 16), the first German troops to return to the country were greeted in a ceremony at the Sarajevo headquarters of the EUFOR force that marked the start of their mission, a German military spokesman said.

Germany will deploy some 30 troops in total to Bosnia by mid-September, returning to the force that it had left at the end of 2012.

Bosnia lies hundreds of miles from the fighting in Ukraine but faces an increasingly assertive Bosnian Serb separatist movement that analysts say has at least tacit support from Moscow.

Nato and senior EU officials have warned that instability from the war in Ukraine could spread to the Western Balkans.

Only days after Russia's invasion of Ukraine, the EU decided to almost double the size of its EUFOR peacekeeping force to 1,100 from 600 troops by sending in reserves to stave off potential instability.

Bosnian Serb separatist leader Milorad Dodik, who has created the gravest political crisis in Bosnia since the war destabilising key state institutions, has said that German troops are not welcome, referring to Germany's role in the World War II.

Dodik also said that he regretted agreeing as a member of the state presidency to extend the mandate of EUFOR.

EUFOR's current mandate runs out in November, and it is up to the UN Security Council to decide on an extension for another year. But concerns are growing that Moscow might use its veto to thwart an agreement.

EUFOR replaced Nato peacekeeping troops in Bosnia in 2004.

The European troops are meant to stabilise the country after Bosnia's Serbs, Croats and Bosniaks waged a war for territory in the 1990s in which 100,000 people died.