The NSW Police embarrassed their federal colleagues by intercepting 220 Glock pistols that had been smuggled into Australia, Premier Barry O'Farrell says.

Mr O'Farrell on Tuesday ramped up his attack on cuts to customs operations, saying the federal government was doing a terrible job of stopping illegal gun imports.

Gun parts and overseas documents suggest the Glock pistols seized in 2012 were successfully imported via Sydney.

"Last year the New South Wales Police certainly embarrassed the federal police with its discovery of the importation through the mail, through a sub-branch of Australia Post, authorised by the federal government, of 220 Glock pistols," Mr O'Farrell told reporters in Sydney.

He said there should be an immediate funding increase for customs to ensure more inspections were carried out, saying the federal government should focus on stopping gun smuggling.

"Frankly, they're doing a terrible job on that," Mr O'Farrell said.

"And they're only able to come here because we have a federal government that seems to look the other way with the illegal importation of guns into this country."