Weapons from the European Union are fuelling one of the world’s most deadly civil wars, an investigation has found.

A four-year forensic study into arms supplies to South Sudan concludes that despite an embargo, weapons from Bulgaria, Romania and Slovakia have been channelled into the five-year conflict which has killed around 400,000 people.

The war has created Africa’s worst migration crisis, with an estimated 2.5 million people fleeing South Sudan and two million displaced inside.

Thousands of assault rifles and millions of ammunition rounds from EU states have reached the war. The EU backs a peace process and is one of the biggest aid donors to South Sudan.

The 105-page report published today by Conflict Armament Research (CAR), says Uganda – a key sponsor of the peace process – was the main conduit for the arms, with the Sudan People’s Liberation Army (SPLA) and its allies obtaining repeated shipments from Bulgaria through Uganda during 2014 and 2015, despite the EU embargo.