US House Speaker John Boehner's office would not confirm or deny a report which said the top Republican has proposed raising taxes on wealthy Americans as part of a deficit reduction deal.

In what would be a significant concession in negotiations to strike an 11th-hour deal, Boehner would agree to let marginal tax rates rise on people making $1 million or more annually, provided President Barack Obama make cuts to entitlement programs, according to the Politico website.

"We have not commented on the content of private discussions, and we're certainly not going to comment on rumors," Boehner spokesman Michael Steel told AFP about the report.

The White House did not respond to requests for comment about the possible offer, for which Politico cited two sources close to the negotiations.

Obama has insisted that any deal to avoid the so-called "fiscal cliff," the combination of tax hikes and mandated spending cuts set to kick in beginning January 1, include a rise in tax rates on the wealthy.

His line in the sand has been an increase in tax rates for households making more than $250,000 per year, but until now Republicans have not budged on tax rates, arguing instead that more tax revenue can be gained by closing loopholes and ending deductions.

A Republican concession on tax rates could mark a significant breakthrough in the negotiations and signal that a compromise might actually be manageable before the end of the year.