It might seem surprising for a spy agency, but ASIO exposed itself to a higher level of public scrutiny than almost every other Commonwealth agency by formally applying for permission to store more than half a million litres of diesel at its new headquarters.

The Canberra Times revealed last week ASIO had applied for permission to keep up to 660,000 litres of fuel to run back-up generators at its new Constitution Avenue home.

Under ACT law, authorisation from the Environment Protection Authority is required to operate a facility designed to store more than 50 cubic metres of petroleum products.

But government departments are almost entirely absent from an EPA list of organisations that have been granted licences.

This is because federal agencies are not required to comply with the ACT law. The only federal government site listed as having EPA authorisation is the Tidbinbilla CSIRO deep space communications complex.

Environment Protection Authority director for environment protection and water regulation Daniel Walters this week praised ASIO for seeking to comply with local environment laws.

''We're very pleased that ASIO, or Finance, has applied for and committed to complying with the ACT's requirements in relation to the fuel storage. I think that's a positive,'' Mr Walters said.

Mr Walters said the EPA would be happy to work with any other Commonwealth agencies that wanted bulk fuel storage licensed.

Construction industry sources said storing more than 500,000 litres would enable ASIO to continue operating its facility for several days if there was a major power disruption.

A Defence spokesman said the Russell Offices complex had diesel fuel storage capacity of 180,000 litres. Most of the fuel storage sites licensed by the ACT Environment Protection Agency are service stations and supply depots.

Others include TransACT at Dickson and the Kingston Railway Station.

The ACT has the strictest bulk fuel storage requirements in Australia.

Fuel would have to be stored in double-walled tanks that are monitored for any losses.

In 1998, diesel fuel that had leaked from a Parliament House tank was found to have seeped into Lake Burley Griffin, sparking a massive clean-up operation.

It was believed that the fuel could have been leaking for several years before it was discovered.

In 2005, a hole in an underground tank at the Chisholm service station resulted in 65,000 litres of fuel contaminating soil and entering groundwater.

An ACT Health Directorate spokesman said less than 30,000 litres of fuel were kept on The Canberra Hospital campus to support several generators.

''Depending on demand, this will support essential services for between 10-24 hours without re-filling,'' the spokesman said.