The EU's top court on Tuesday required Greece's farmers to repay 425 million euros in emergency aid to Athens authorities, confirming a decision that the money was in fact an illegal state subsidy.

The decision lands at a sensitive time in Greece, with farmers angry over deep tax and pension reforms required in the country's 86-billion-euro ($95 billion) bailout.

The case dates back to 2009 when 800,000 Greek farmers received the aid after bad weather in the region, but the European Commission, the EU's anti-trust regulator, declared the funds an illegal state subsidy.

The court in a statement said that Greek authorities failed to demonstrate "specific exceptional circumstances in the Greek agricultural sector" as compared to other EU member states.

Crucially, the commission also accused Greece of appropriating funds to its national budget that should have been set aside as insurance for farmers against bad weather and disasters.

With the decision, Greek farmers will on average be required to repay about 500 euros per farm, the court said in a statement.

A spokesman for the court said Greece must recover the aid "within a reasonable delay", without providing further details.