Farmers in Greece blocked major highways and border crossings on the Greek border with Macedonia and Turkey in protest of proposed cuts to the debt-ridden country's pension system.

The protests come as international lenders began reviewing Greece's progress in implementing reforms set out in its multi-billion euro bailout.

Labor unions across the country have called for a nationwide strike against the reforms, which Greece's international creditors, including the International Monetary Fund (IMF) and European institutions, said must be approved in order to unlock further aid.

Tsipras' proposal could witness pensions cut by 15 percent, a figure that protesters say undermines their social security system.

In 2015, Greece witnessed a turbulent battle with its lenders that witnessed anti-austerity Prime Minister Alexis Tsipras call for a referendum on succumbing to the EU and IMF's demands as well as a snap election considered a confidence vote for his government.

Tsipras' Syriza party managed to clinch a victory at last year's polls, effectively giving the leader's government the popular support it needed to negotiate the terms of a third bailout plan in five years.

However, Thursday's general strike may pose challenges to Tsipras' government as it attempts to shore up support from its lenders for a positive review of its reforms program. Public servants, journalists, lawyers and farmers, among others, are expected to join Thursday's general strike.

ls/kms (dpa, EFE, Reuters)