The cost of fighting wars in Iraq and Afghanistan could eventually cost the U.S. government $811 billion US, says a new Congressional study.

An excerpt from the BBC story:

It estimates that Congress has appropriated $368bn for the global war on terror, including both conflicts.

It says that if the current spending bill is approved, US war costs will reach $439bn, and it estimates that an extra $371bn may be needed by 2016.

On that basis, the two wars would cost more than the $579bn spent in Vietnam.

The future costing assumes that US troop levels will drop from the 258,000 currently engaged in all operations to 74,000 by 2010.

Budget gap

The rising cost of the war is leading to growing concerns in Congress, where attempts to control the budget deficit have been hindered by the "supplementary" requests received each year for war spending.

The CRS estimates that the US Department of Defense's annual war funding has risen from $73bn in 2004 to $120bn in 2006, with an increase of 17% this year alone.

There have also been concerns that extra non-related appropriations are often tucked inside the war funding bill.