Leaked emails from two regional commanders show the Border Force is taking dramatic action in the face of "significant budget pressures", including slashing casual staff by up to two-thirds in some areas. Sources say the organisation is becoming increasingly casualised, which suggests the reduction in overall workers will be substantial.

“The department is facing significant budget pressures and it has been decided that it is prudent to introduce measures to address these pressures,” a leaked email from Western Australia regional commander Rod O'Donnell said.

In one email to staff, acting regional commander for Victoria and Tasmania Greg Dowse said the entire Department of Home Affairs, including the Border Force, is implementing "significant measures" to ensure budgets are met, including "a reduction in the number of attendances that are offered to intermittent and irregular employees", or casual workers. Sources say the changes will mostly affect airport staff.

Mr Dowse says the national decision was "not taken lightly" and affected staff have been offered counselling.

A separate leaked email to staff sent by Mr O'Donnell said after receiving a revised budget "I will only be able to afford around one third of the current level of [casual staff] usage going forward". He confirmed this applied to "aviation operations" and would come into effect from December 17.

Mr O’Donnell said a similar staff reduction strategy was under way nationally to address the budget situation.

The announced cuts to the casual workforce were "a starting point" and further measures may be necessary "should the overall budget saving measures not be sufficient".

"I am conscious that this will have an impact on yourselves and your families and comes at a challenging time of the year ... I accept that the timing of this decision is not good,” he said.

Border Force insiders said the announcement had caused anxiety among staff. Casuals were devastated at the prospect of being out of work over summer. Workers likely to remain employed were questioning how they would securely process passengers and luggage with so few staff, at what is traditionally the busiest time of year at airports.

Other Border Force staff said casual shifts at airports had been dwindling for some time, causing distress for those who had given up other work to join the organisation.

If the department hadn’t made cuts across the board, it was looking at a deficit of around $300 million for the financial year, according to the main public sector union.

Community and Public Sector Union deputy national president Lisa Newman said it had received reports of major cuts to front-line operations across the country, potentially affecting thousands of casual staff at airports and elsewhere.

"The blame for this catastrophic budget blowout lies squarely with senior management in Home Affairs," she said, adding that halfway through the financial year the agency was on track for a budget deficit of at least $300 million.

There have also been reports that staff employed to handle freight in Melbourne have been redeployed to passenger processing to cover gaps in staff members.

"This is a dangerous time of year to be cutting front-line capacity. There’s always a big jump in passenger numbers and freight over Christmas, so the department can only plug the gaps in one area by opening up holes in another," Ms Newman said.

The Canberra Times also understands that a fleet of fast-response Border Force boats deployed to combat security threats in the Torres Strait have been pulled from service. The boats respond to suspected activity such as unauthorised boat arrivals, smuggling of goods and illegal fishing on a maritime border considered particularly complex and challenging.

The union said it had been informed by members that fast response boats "will be taken out of service prior to Christmas" for an unknown period and crew members will be redeployed.

"Clearly this decision has been made at least partly because of budgetary pressures," Ms Newman said, adding that Border Force staff believed the boats "should be available for deployment at all times".

Recruitment for visa processing staff in Hobart was also halted as part of budget cuts across the country.

“Visa processing times are already unacceptably long and halting recruitment means they’re only going to get worse,” Ms Newman said.

A department spokesman confirmed Home Affairs and Border Force had been cracking down on spending since November 1, but did not confirm the $300 million figure.

"This is necessary to ensure that the department and ABF operate within resourcing parameters, are fiscally responsible and deliver our objectives consistent with available funding, and while balancing risks, priorities and resources," the spokesman said.

Measures in place to stop spending included "recruitment controls to ensure staffing is within allocated FTE and ASL caps", a freeze on engaging all new non-project contractors and consultants, and restricting travel budgets. Some existing contracts are also being targeted for review.

"These saving measures are being deliberately implemented before the end of the financial year to allow time for them to be effective and will be regularly reviewed and updated where necessary," the spokesman said.

The cuts to Border Force staff came just weeks after budget pressures also led to hundreds of IT contractors being shown the door at Home Affairs in Canberra, in many cases with just a week’s notice. Between 170 and 300 contractors were affected by the cuts, with hiring for other “non-project” IT contractors frozen due to a “forecast overspend”, an email to staff said.