Another 100 jobs are set to be cut from Customs and Border Protection before the end of the financial year, according Australia’s biggest union looking after public servants.

It means the agency looking after the integrity of the nation’s borders has lost 840 staff in six years.

The Community and Public Sector Union’s deputy secretary Rupert Evans said staff were continually complaining it was harder to maintain quality.

“The thin blue line just keeps getting thinner in the service,’’ he said.

“It’s not just us saying it - last year Customs (chief executive) Michael Pezzullo told Senate Estimates there was no more fat to cut in the service and that any further cuts would ‘go through the bone and out the other side’.

“There is no hiding from the fact that cutting Customs jobs increases the risk of drugs and firearms being smuggled into the country, and will lead to porous borders.

‘‘Each year Customs gets busier not less so if significant gaps are emerging in those services then this Government needs to tell people.”

He said Customs informed staff this week that it would undertake a targeted program of 100 voluntary redundancies by June 30 to reduce full-time equivalent staff numbers to 5000.

“We are talking about real people performing vital necessary services,’’ Mr Evans said.

‘‘Unfortunately neither of them are asking the question – how many people do we need to do the job?”