Strikes that promised disruptions at Melbourne airport, Medicare, Centrelink fail to impact day-to-day operation

Thousands of public service workers have packed out Melbourne's Town Hall in the union's largest stop-work service in a generation, but the promised disruptions at the city airport, Medicare and Centrelink have failed to materialise.

The Community and Public Sector Union has called for members to walk off the job for four hours from 10am (AEST) today for a stop work rally in the Victorian capital, in protest to what the union claims are "draconian" attacks by the federal government on its working conditions.

CPSU spokesman Chris Taylor, on the ground in Melbourne, said up to 2000 workers had packed out the lower floor of Town Hall.

"The government has forced us into taking action," he said.

"(CPSU members) don't like to stop working, but they've had to in order to fight the Abbott government's harsh bargaining measures.

CPSU national secretary Nadine Flood said the government had refused to negotiate a sensible agreement with the union.

"Customs officers could lose up to $8000 a year from their take-home pay because allowances are being slashed while part-timers and casuals in Centrelink and Medicare would get less money for doing the same work," she said.

"Thousands of public sector workers face a cut in their current take home pay, with reduced allowances, cuts to rights and penalty rates plus increased hours, all of which will cost them far more than a 1.5 per cent pay offer would deliver."

The CPSU said services at Melbourne airport would be disrupted, as well as at Centrelink and Medicare.

However, the airport has said extra staff would be on hand to make up for the shortfall.

Passengers are still advised to arrive early while the strike is taking place.

A spokeswoman for the Department of Human Services said the state's Centrelink and Medicare services had not experienced significant delays so far.