Government documents show the Department of Defence has been fined $4.93 million for false fire alarms in just three years.

The most recent bill – disclosed on the government tender website last month – cost $91,735.

Some of the earlier bills sent hundreds of thousands of dollars up in smoke.

Defence points out it is responsible for 111 sites across the country, comprised of 25,000 buildings. Nonetheless it says it's trying to bring down the number of false fire alarms.

"After any false alarm the department undertakes a post review of the call out to determine the cause and the necessary actions to minimise any future call outs," a spokesman told Fairfax Media.

"The department regularly communicates with staff on how to avoid causing false fire alarms."

The department's response – which took 12 days – says the $5 million also covers security and fire panel inspections and the maintenance and installation of fire systems. However, the 16 relevant contracts are all clearly labelled "false fire alarms fines" and there are dozens of other contracts for installations and inspections.

Firefighting agencies across the country have introduced hefty fines of between $750 and $1250 in an effort to prevent false call outs.

However, the fines typically don't cover the full cost to the firefighters of the emergency call out, which is estimated to be closer to $3000.

They say false alarms increase the risk of accident and injury to firefighters and the general public, clog up the 000 system and cause delays to response times for genuine emergencies.

The main causes of false alarms include burnt toast, cooking fumes, aerosol sprays, cigarettes and candles and poor ventilation.