Staff at 13 federal departments and agencies walked off the job on Monday morning as part of a rolling campaign designed to break a two-year deadlock on pay and entitlement negotiations.

The strike action, announced three weeks ago and led by the Community and Public Sector Union, caused delays for those accessing Centrelink and Medicare services with clients urged to avoid non-essential inquires.

Staff at Medicare, Centrelink, the Australian Tax Office, Defence, the Bureau of Meteorology and the Australian Bureau of Statistics all launched 24- hour strike action on Monday.

Officials within the Prime Minister's own department walked out on the same day he pulled the trigger on a double dissolution election on July 2.

The strike action also affected the Department of Education, Department of Environment, GeoScience Australia, IP Australia, the Australian Synchrotron and the Administrative Appeals Tribunal.

The coordinated campaign has prompted the Department of Immigration and Border Protection to warn of lengthy delays at international airports on Thursday with customs officials set to withdraw labour.

Department of Agriculture staff working in biosecurity will also walk off the job on Thursday with rolling industrial action to continue at airports in coming weeks.

DIBP assistant commissioner Clive Murray said strikes would cause unavoidable and inconvenient delays.

"We have contingency plans in place to maintain the integrity of the border and limit as much as possible the impact of this action on travellers," he said.

"However, delays will occur and those travelling overseas over the Easter period are encouraged to arrive early at the airport, and then to proceed directly to customs and immigration clearance."

CPSU national secretary Nadine Flood acknowledged the strike would frustrate those boarding flights and accessing key government services such as Medicare and Centrelink.

"That's unfortunate, but two years into this dispute, these workers still face an attack on their family-friendly rights and other conditions of work," she said.

"The extent of this mess is underlined by the fact that after two years more than eight out of 10 people working in the public sector still don't have a new agreement."

A Qantas spokeswoman said the airline was preparing for disruptions continuing into April.

Similar work stoppages were held by customs and immigration staff in September at airports in Sydney, Brisbane, Perth, Adelaide, Darwin, Cairns, and the Gold Coast.

Immigration is the latest in a string of large departments to have rejected revised pay proposals, following no-votes at the Tax Office, Human Services and the narrow rejection of a deal at Defence. Staff at Prime Minister and Cabinet also voted down an enterprise agreement last month.

On Monday, air traffic controllers and technical staff employed by the Department of Defence walked off the job and are expected to do so again on Thursday.

"Further 24-hour stoppages will occur this Easter Thursday in support of striking Border Protection staff by Defence staff from RAAF Bases Williamtown and Richmond in NSW," a union official said.

Strike action at the Australian Tax Office was supported by the Australian Services Union; although representatives warned only CPSU members are protected against adverse action under the Fair Work Act.

ASU tax branch secretary Jeff Lapidos said, "We certainly support the CPSU's right to take this industrial action.

"But we intend continuing our campaign for a much better offer from the commissioner and we are planning to take other industrial action that our leadership thinks will be more effective."

Department of Human Services general manager Hank Jongen said the strike action stretched the department's resources and punished those who relied on government support.

"Our advice to customers is – if you don't need to contact us urgently, consider delaying your visit or contacting us another time," he said.

A spokesman for Employment Minister Michaelia Cash said it was unfortunate the CPSU had resorted to strike action.

"This can cause harm to the public and involves a loss of pay for employees," he said.

"Instead of resorting to industrial action the CPSU would better serve the interests of their members if they were to genuinely negotiate in good faith."