By Ambrose Evans-Pritchard

LONDON, England - December 8, 2010 - Agreement in Washington on a fresh fiscal package has set off dramatic rise in yields of U.S. Treasuries and bonds across the world, threatening to short circuit any benefits of stimulus. The bond rout raises concerns that the U.S. authorities may be losing control over events.

The yield on 10-year Treasuries - the benchmark price of money worldwide and the key driver of U.S. mortgages rates - has rocketed to 3.3%, up 35 basis points, since (illegitimate) President Barack Obama agreed on Monday to compromise with Senate Republicans on tax cuts.

The Treasury sell-off has ricocheted through the global system, triggering bond sell-offs in Asia, Europe and Latin America. Japan's finance ministry braced as borrowing costs on seven-year debt jumped by a sixth in one trading session, while German Bunds punched through 3%.

The White House deal with Congress will renew the Bush tax cuts for rich and poor alike for two years, as well as adding a further a 2% cut in payroll taxes and an extension of unemployment aid.

David Bloom, currency chief at HSBC, said it is hard to disentangle whether investors are shunning bonds because they expect U.S. stimulus to boost growth next year, or whether they are losing patience with profligacy in Washington.

"If this is all about growth, that's brilliant. But if yields are rising because people think America's fiscal situation is unsustainable, then its Armaggedon," he said.