WASHINGTON, May 7 (Reuters) - As skyrocketing food prices deepen global hunger, the U.S. Senate is seeking $850 million in last-minute funding for emergency food aid this year, $500 above what President George W. Bush had requested.

Sen. Herb Kohl, the Wisconsin Democrat who chairs a subcommittee on agriculture appropriations, said lawmakers would seek the additional food aid funds as part of a massive Iraq war funding bill.

Kohl said in a statement that an extra $395 million would also be sought for fiscal 2009 in the Appropriation Committee's final version of the supplemental bill in order to help cope with a "perfect storm" of hunger.

"The world's supply of food is down, while food demand is up, food costs are skyrocketing and entire societies are falling apart as a direct consequence," he said.

The House of Representatives, as well, is angling to add $500 million to the $350 million the Bush administration has requested in supplemental food aid funding for fiscal 2008.

In recent years, supplemental funds for food aid have become a regular addition to annual budgeted funds.

The war funding bill is scheduled to be debated on the House floor and also in the Senate Appropriations Committee on Thursday.

It was unclear if Bush, who has said he wants a supplemental bill worth $108 billion, will veto the measure if it is too large or if it shackles him in Iraq.

The United States, the world's top donor of food aid, has provided around $1.6 billion to $1.7 billion in recent years through the Agency for International Development.

But its aid budget, and that of other donors, has been able to buy far less food this year due to the spiraling prices for food, which jumped 43 percent globally through March, and for crude oil, which has forged new ground above $120 a barrel.

Bush has said he's deeply concerned about the global food price crisis, and last week asked Congress for the extra $395 million in emergency food aid in 2009 as part of a package of $770 million in food assistance and agriculture development.