Australian Electoral Commission figures released yesterday show Labor had a significant financial advantage heading into the election.

In the 2007-08 financial year, Labor raised $12.6 million in donations. The Liberal Party raised $8.3 million and the National Party raised $944,074. The Federal Government said the release of the figures showed the need for further tightening of campaign finance laws.

"In election year 2004-05, when the disclosure threshold was $1500, 1286 donor returns were disclosed," the Special Minister of State, John Faulkner, said. "In the run-up to the 2007 election, with a disclosure threshold of more than $10,000, only 334 donor returns were received. For election year 2007, where political expenditures reached a massive $212 million, it is impossible to track the identities of many donors."

The Government introduced changes to Parliament last year requiring the identity of all who donated more than $1000 to be revealed as well as a ban on donations from overseas.

But the Opposition has delayed consideration of the changes. It says it wants them to be examined at the same time as a further tightening of electoral laws. The second wave of changes have only been canvassed in a green paper, but suggest banning all private donations in favour of higher public contributions, which would remove any undue influence from the donation system.

The Opposition's shadow minister of state, Michael Ronaldson, said the latest electoral funding figures showed Labor was still beholden to the union movement.

"Despite unions representing only 17 per cent of Australian workers, Labor's archaic membership rules require that all their MPs be union members. It would appear that whoever pays the piper still calls the tune," Senator Ronaldson said.

The biggest union contributions came from the Shop, Distributive and Allied Employees Association, the Construction, Forestry, Mining and Energy Union and the Communication, Electrical and Plumbing Union. Each contributed between $1 million and $1.5 million.

Unions spent $3 million on political campaigning in 2007-08; $9.2 million went directly to the Labor Party while a further $26.8 million was spent on their own campaigns.

This is on top of the $10 million the ACTU spent in the previous year on the highly successful Your Rights At Work campaign.

The Greens support a ban on all private donations. "As a matter of democratic principle, elections should give voters fair access to all parties' policies, and public funding is the most even-handed way to ensure this outcome," Senator Bob Brown said.

Under electoral law, political parties have to give the electoral commission details of how much they raise and spend each financial year.

Recent changes mean that interest groups that campaign on election issues must now also disclose their spending.