Centrelink urged clients to stay away from its offices and phone lines on Friday as thousands of its officials planned to walk off the job, with the welfare agency claiming the actions of the Community and Public Sector Union were "frustrating".

The Immigration Department has warned of possible disruption at international airports around the country and warned travellers to show up early for their flights.

The strike action is part of a broader protest across several federal government departments and agencies whose workforces have been in dispute with the Coalition government over wages and conditions for more than three years.

CPSU National Secretary Nadine Flood took aim at the government on the eve of the strike, claiming the three-year dispute amounted to "1000 days of incompetence" by the Coalition.

"These people are the engine that runs the public services that Australians know and rely on, yet they've been forced to fight off the Turnbull government's attacks on their rights and livelihoods for more than 1000 days," the union leader said.

"These workers are striking to hold the government accountable for this debacle.

"We started bargaining with this government in late 2013 but around 100,000 Commonwealth public sector workers still don't have new enterprise agreements, despite these workers' ongoing willingness to talk and compromise."

Centrelink insists payments due on Friday will not be affected by the strike but the welfare agency's parent department Human Services Centrelink media manager Hank Jongen said Medicare and Child Support customers may be affected by industrial action planned by members of the CPSU.

"Customer payments will not be affected by the industrial action, however we may have reduced numbers of staff in service centres and on the phone, and increased wait times," Mr Jongen said.

"We have put in place contingency arrangements to make sure staff are available to help people who are in financial hardship and need immediate assistance.

"However, we ask customers with non-urgent business to consider contacting the department another time to free up staff to help those who need it."

Mr Jongen said he was frustrated and blamed any disruption on the union.

"The union's decision to proceed with the disruption of services to customers is frustrating given the department's genuine attempts to progress negotiations," he said.

"We are concerned the union is encouraging its members to take counterproductive industrial action which will inconvenience people across Australia, including some of the most vulnerable in our community."

Few Immigration or Border Force public servants are expected to participate in Friday's strike but a statement by Immigration warned travellers of stop-work actions planned around the country.

"People travelling internationally by air on Friday September 9 are being urged to arrive at the airport early to avoid delays due to protected industrial action.

The Department of Immigration and Border Protection has been advised that some employees, including from the Australian Border Force who are members of the Community and Public Sector Union will take part in the stoppage.

"The stoppage will commence at 8.30 am and conclude at 11.30 am local time in NSW, Queensland, Victoria, Tasmania, WA, SA and NT.

"A stoppage in the ACT will also commence at 11.30 am and conclude at 2.30 pm local time."