TAXPAYERS are forking out more than $1.4 million a year just to supply cigarettes and tobacco to immigration detainees.

While the Federal Government spends millions on anti-smoking campaigns to cut smoking rates among Australians, the cost of keeping up detainees' smoking habits is racking up a bill of about $4000 a day.

The Opposition has accused the Gillard Government of providing its own "mini-stimulus" package for the tobacco industry.

Detainees can earn points in the immigration detention system worth up to $50 a week by participating in education and activity programs, which they can then use to purchase items, including cigarettes and tobacco products or phone cards.

The figures were released in an answer provided by the Immigration Department to a question asked by Liberal Senator Michaelia Cash in Senate estimates hearings.

It revealed that Serco, the company that manages the detention centres, has spent on average $1.4 million a year on tobacco products for detainees since the 2009-10 financial year.

The Government has warned that the bill will continue to rise if the Coalition maintained its refusal to support legislation allowing the Government to pursue off-shore processing of asylum seekers, namely the revival of the Malaysia people swap deal.

The Bill to overturn the High Court decision to rule offshore processing illegal is expected to be voted on next week in Federal Parliament, but will be rejected by the Coalition.