Greece was hit with a news blackout Wednesday as the country's journalists walked off the job over a controversial pension reform, a day before a general strike on the same issue.

The 24-hour labour action is directed against government plans to lower the maximum pension to 2,300 euros ($2,500) a month from 2,700 euros currently and introduce a new minimum guaranteed basic pension of 384 euros.

The leftist administration of Prime Minister Alexis Tsipras also wants to merge pension funds and increase social security contributions by both employers and staff.

The plan has been criticised by a wide array of professional classes, from lawyers and engineers to sailors and farmers, and Greek unions have called a general strike -- the third in as many months -- on Thursday.

The farmers have formed protest hubs at dozens of locations on Greece's national highways, intermittently blocking traffic with tractors over the past two weeks.

On Tuesday the farmers blocked passage of freight trucks into Bulgaria and Turkey, causing long lines on the respective borders.

Greece must save 1.8 billion euros from state spending on pensions under a three-year bailout signed with the European Commission, the European Central Bank and the International Monetary Fund in July.

The Tsipras government has warned that the nation's pension system will soon collapse without the reform, which is expected to be put before parliament for a vote later this month.