Scott Morrison's departments employ more than 95 communications staff and spin doctors, costing taxpayers at least $8 million a year.

Details released to the Senate show the departments of Immigration, Border Protection and Australian Customs have 85 permanent and 10 other staff responsible for media monitoring, internal communication and public relations.

This is estimated to cost between $8 million and $9.2 million a year in salaries alone, not including superannuation, leave, allowances and other costs. The details were released in response to questions asked by Labor senator Joe Ludwig.

Mr Morrison, who regularly uses the adjectives ''on water'' and ''operational'' to describe matters he will not discuss, said through a spokeswoman that ''any suggestion these staff are all working on the minister's liaison with the media is completely untrue''.

''These are large organisations, which require a significant amount of internal and corporate communication work on behalf of these agencies,'' the spokeswoman said.

According to media transcripts available on his website, Mr Morrison and Angus Campbell, the commander of Operation Sovereign Borders, have used the ''on water'' and ''operational'' lines at least 30 times to deflect questions from journalists.

The Sunday Age reported in March that at least 66 spin doctors worked in the department under Mr Morrison. In a statement to Parliament he rejected the report and said he had only 37.9 people in communications, whereas the previous Labor government employed 44 people in this area.

Asked to explain the difference between the two figures, the spokeswoman said: ''The minister was referring [in March] to the national communications branch of the Department of Immigration and Border Protection.

''It is important to note that of the 37.9 staff (including two seconded to Operation Sovereign Borders) in that branch as at 30 April, 2014, only a third of those staff were working in the media section of the branch.

''The rest of the branch undertakes other communications work, such as campaigns and marketing, internal communications, social media, graphic design and broadcast production.''

Mr Morrison has employed a deliberately secretive approach to Operation Sovereign Borders and says doing so has contributed to the program's success in ''stopping the boats''. It has now been more than 160 days since the last successful people-smuggling venture to Australia - a point noted in a press release on Friday afternoon.

''Over the same period last year under the former Labor government, more than 150 boats with more than 10,000 people on board arrived illegally,'' it said. Last May alone saw almost 3300 asylum seekers arrive on boats.

In recent months, as it has become apparent Mr Morrison has ''stopped the boats'', his colleagues say he has become more relaxed and is more available than other ministers who are ''up to their necks'' with problems.