Greece's Ambassador to Bulgaria has been informed by the country's Transport Ministry of its concerns over the situation at the common border, officials say.

Sofia is now calling on Athens to secure a passage for transit trucks, with Bulgarian PM Boyko Borisov having spoken to Greek counterpart Alexis Tsipras over the phone and urging him to "take measures".

This comes amid protests of Greek farmers over planned reforms to pensions legislation and to the distribution of subsidies which are to be suspended for a number of farmers.

By Tuesday morning, a 15-km-long queue was formed on the Bulgarian side of the border at the Kulata crossing. As of  Tuesday evening, some trucks have been waiting for 28 hours.

"Strikes are strikes; however, domestic affairs [in Greece] should not violate [EU] freedom of movement," Bulgarian Foreign Minister Daniel Mitov has told journalists.

The Bulgarian Road Infrastucture Agency (RIA) has issued a statement advising drivers who are to travel to Greece in the coming days to plan their route "carefully", due to the blockade at Kulata-Promachon border crossing and the intermittent blockades set up elsewhere along the border. RIA has secured 12 chemical toilets at the abovementioned crossing to meet the needs of waiting drivers.

Blockades have been staged elsewhere along the border over the past few hours, with protesters at Ilinden-Exochi observing previously declared hours of the blockade. The current blockade, which began at 17:00, is due to continue until 22:00 local time (EET).

At the Makaza pass, Bulgarian-plated vehicles are not being let into and out of Greece at the moment, Bulgarian media report.

It is Kulata, however, where vehicles are facing the biggest problem, with farmers not abiding by the notices they are giving to the police beforehand on the timing of blockades. The latter detail has been communicated to H.E. Dimosthenis Stoidis, who has said the problem would not be solved before February 04 when a general strike has been scheduled.

Cars and trucks carrying medicine both ways are granted passage by the farmers through all checkpoints.

But Transit trucks carrying other goods are severely affected, with drivers, and also employer unions, complaining of substantial losses incurred, estimated at BGN 0.35 M a day according to a businesses representative.

The Bulgarian National Television reports that tour operators have canceled a number of travels to Greece.