Bulgarian truckers sealed off all six checkpoints along the country's land border with Greece on Friday to protest at weeks of intermittent blockades by Greek farmers that have disrupted road traffic.
Parliament issued a special declaration urging the European Commission to start an infringement procedure against Greece for violating EU laws on the free movement of goods.
Bulgarian Prime Minister Boyko Borisov has also intervened in the feud, accusing Greece on Thursday of "purposefully tormenting Bulgarians".
Greek farmers have demonstrated for more than a month against pension and tax reforms demanded by the European Union in return for bailout funds, blocking roads into Bulgaria and across Greece with tractors.
Bulgaria's busiest Kulata-Promachonas checkpoint has been shut for all vehicles since Tuesday and truckers stepped up their action on Friday by blocking all six posts along the 430-kilometre (270-mile) frontier, border police said.
The action forced traffic to divert through neighbouring Former Yugoslav Republic of Macedonia (FYROM) and Turkey for as long as the protest action continues.
Bulgarian truckers' unions are angry over the Greek farmers' protests that have blocked the passage of freight trucks, disrupting traffic and inflicting huge losses on the freight companies.
Vast queues of trucks and cars lined up at the border crossings on Friday and only pedestrians were allowed to cross.
Truckers have vowed to maintain the blockade until the Greek farmers remove their tractors and free up all roads into Bulgaria.
The EU member has the fifth-largest number of trucks in the European Union, according to unions figures.
"Hundreds of Romanian, Polish, Hungarian, Czech, Austrian truckers are also stuck at the border," Krasimir Lalov, deputy chairman of the National Union of Bulgarian Freight Forwarders told AFP after returning from the Kulata checkpoint on Friday.