Greek farmers continued their nationwide blockades on Tuesday, disrupting traffic along major motorways and intermittently closing border crossings to protest delays in farm aid payments.

Farmers have deployed thousands of tractors and trucks in dozens of blockades as they face a shortfall of more than €600 million ($698.6 million) in European Union aid and other payments.

The delays were prompted by investigations into a corruption scandal in which some farmers, aided by state employees, allegedly faked land ownership to qualify for payouts. Ongoing audits have slowed subsequent disbursements.

The delays to funding come just as farmers and stock breeders struggle with an outbreak of sheep pox that has led to hundreds of thousands of sheep and goats being culled.

The nationwide demonstration on Tuesday disrupted traffic at several junctures along two highways linking Athens to the northern city of Thessaloniki and the western port of Igoumenitsa to the Turkish border in the east, both key transport routes for trade directed to the Balkan countries.

“It’s a matter of survival,” Yiannis Koukoutsis, a farmer from the central agricultural region of Larissa, told public broadcaster ERT. “We’re looking for moves of good faith from the government, including freezing tax debt.”

The centre-right government of Kyriakos Mitsotakis, under criticism over the scandal, has said it was open to discussions and urged farmers to terminate the blockades. It has acknowledged delays in payments and said farmers will be getting more aid this month before they finally receive a total of €3.7 billion this year.

But protests continue. In the north, farmers intermittently restricted traffic through the Promachonas and Kipi border crossings with Bulgaria and Turkey and said they aimed to block the port and airport in Thessaloniki this week.

On the island of Crete, three flights were cancelled and several others delayed after a group of farmers threw stones at police and stormed onto the runway at the Heraklion airport on Monday.

Airport operations resumed around 8am GMT on Tuesday, Greek aviation officials told Reuters, after farmers left.