ATHENS Ferries remained docked at Greek ports and farmers poured milk onto the streets on Wednesday in protest over plans to revamp Greece's pensions system, a condition for the country's multi-billion euro bailout.

Public anger is growing Pension over the leftist-led government's drive to cut its costly pension bill by some 1.8 billion euros this year, the equivalent of about 1 percent of national output.

Public and private sector workers plan a national walkout on Feb. 4 but ship workers took early action on Wednesday by starting a 48-hour strike that brought passenger shipping activity in the seafaring nation to an effective standstill.

"This is a first response to the third (bailout) maelstrom," the PPM Panhellenic Seafarers' Federation said in a statement. Under reform proposals, their own contributions fund will be merged with another, sparking concerns about lower pensions in future.

On the Aegean island of Naxos, where farming accounts for 50 percent of the local economy, farmers gathered at its port to pour away milk. In the city of Thessaloniki in northern Greece, farmers gathered with their tractors to protest.

"The government is planning to double our taxation ... and triple our pension contributions. This is unacceptable, they will exterminate us", said Vagelis Boutas, president of a national committee coordinating the farmer protests.

"We will escalate our demonstrations from tomorrow," he told Reuters.

Debt-ridden Greece has made many failed efforts in the past decades to revamp its ailing pension system, the most expensive in Europe as a percentage of economic output. Experts have in the past warned it will collapse if left unchanged.

Pension reform is a particularly sensitive issue for the Tsipras government, engaged in a delicate balancing act to push through controversial reforms in a fractious parliament where it has a slim majority of just three seats.

Athens signed up to a bailout deal with international lenders last year worth up to 86 billion euros, yanking the country from the brink of financial meltdown.

It has presented a plan which increases social security contributions and recalculates future pensions but has also promised to protect pensioners on whom entire households can sometimes depend.

After tough negotiations and months of resistance to calls by lenders, Tsipras agreed last year to implement a 2010 law that included discouraging early pensions and raising the retirement age.

(Writing By Michele Kambas; Editing by Gareth Jones)