WASHINGTON — Warren Buffett will have to contribute $49,000 from his multi-billion dollar fortune after a Republican congressman took up his dollar-for-dollar challenge for donations to help cut the US deficit.

Virginia Congressman Scott Rigell was the first to take up the challenge of one of the world's richest men, telling Buffett that last year he donated $23,103.33, or 15 percent of his salary, to help the government reduce its $15.2 trillion in debt.

Rigell said he expects to donate $26,100 more this year -- meaning Buffett will have to pony up just over $49,000.

"I appreciate and gladly accept your generous offer to match contributions that Republican members of Congress make to pay down the federal debt," Rigell, a car dealer before he joined Congress, wrote to the world-famous investment tycoon last week in a letter released Wednesday.

"Though we differ on tax policy, as fellow Americans and businessmen I know that we share a common bond: a deep concern over the state and trajectory of our country's finances."

It was the first response to Buffett's challenge, issued in a January 11 interview with Time magazine, to Republicans who suggested that volunteer donations to bring down the country's debt mountain are better than raising taxes on the wealthy.

If that is their true belief, Buffett said, they should all join hands in the effort.

"If we go to a contribution system, I'll match the total contribution made by all Republican members of Congress," he said.

Last year Buffett, whose fortune from his Berkshire Hathaway investment group is put at some $50 billion, said that at 17 percent, he pays a lower tax rate than his own secretary.

He used those figures to call on Congress to raise the rate of taxation for the wealthiest.

But some Republicans ridiculed Buffett, saying he should just go ahead and send in the money himself.

In a letter back to Rigell obtained by US media Wednesday, Buffett replied that he "will be delighted to match" Rigell's donations.

"I plan to send along my match to the Treasury around April 20th, after I've had a chance to hear from everyone.

"You are the first to respond, but I hope your action spurs an intramural rivalry between Republicans and Democrats."

The news of the first taker to Buffett's challenge came days after Mitt Romney, the multi-millionaire widely expected to be the Republican challenger in November's presidential election, said he pays an effective tax rate of around just 15 percent on his income -- less than much of the country's middle class.