Administration and congressional officials said on Monday that the new request would come on top of the $25 billion in emergency spending already approved for this fiscal year.
That means funding for military operations in Iraq and Afghanistan will total nearly $105 billion in fiscal 2005 alone - a record amount that shatters initial estimates of the cost.
In addition to money for troops in Iraq and Afghanistan and for new army equipment, up to $650 million is expected to be earmarked for humanitarian, reconstruction and military operations in Asian nations devastated by last month's tsunami, congressional aides said.
The administration is considering debt relief for Indonesia, the hardest-hit country, they added.
The funding request comes as the US army says it is now planning to keep at least 120,000 troops in Iraq for the next two years to train and fight alongside Iraqi forces against those opposed to their presence.
The army total is part of a force of 150,000 American soldiers, marines and other troops now in Iraq.
White House officials declined to comment on the size of the package or when it would be unveiled. But administration and congressional sources said they expected a White House announcement on Tuesday.
"We are dealing with a country [Iraq] that can really finance its own reconstruction and relatively soon"
US Deputy Defence Secretary Paul Wolfowitz before the war
The funding request is expected to be formally submitted to Congress after President George Bush sends up his fiscal 2006 budget on 7 February.
Democrats have accused Bush of excluding Iraq-related costs from previous budgets to meet his deficit reduction goals, a charge the White House denies.
But congressional sources said they expected the White House this year to incorporate the spending request into its budget deficit projections.
The White House is bracing for a backlash from Democrats and some Republicans.
At nearly $105 billion, total funding for military operations in 2005 would be more than 13 times larger than Bush's budget for the Environmental Protection Agency and would be nearly as big as the state of California's annual budget.
In addition to money for military operations, at least $780 million in the package would go to combat the drug trade in Afghanistan.
The administration is also considering including $1 billion to $2 billion to construct a new US embassy complex in Baghdad.
Administration and congressional officials had initially expected this year's supplemental spending to total closer to $50 billion. But cost estimates have skyrocketed to as much as $100 billion as the anti-US movement in Iraq has intensified.
Critics have long accused Bush and his advisers of understating the costs.
Before the invasion, then budget director Mitch Daniels predicted Iraq would be "an affordable endeavour" and Deputy Defence Secretary Paul Wolfowitz assured Congress: "We are dealing with a country that can really finance its own reconstruction and relatively soon."
Not including the new funding request, Congress has so far approved $120 billion for Iraq and another $60 billion for Afghanistan. Last year it also approved a $25-billion contingency fund for the Pentagon.
Yet only a fraction of the $18.4 billion set aside for rebuilding Iraq has been spent. The White House blames fighters for the slow pace of reconstruction.