Irresponsible "Tea Party" Republicans have shut down the US federal government in a flailing attack on President Barack Obama's healthcare laws.

Congress failed to set a budget by Monday's midnight deadline and now sees the first shutdown in 17 years.

Republicans had continually tried to tie new government funding to attempts to axe funding for, delay or wreck Mr Obama's healthcare structure.

An angry Mr Obama used a press conference to condemn the Republicans' "ideological crusade to deny affordable healthcare" to millions of US citizens.

"They don't get to hold the entire economy hostage over ideological demands," he said.

But their effort was countered by the president's allies in the Democratic-led Senate, leaving the government in limbo when its money ran out at the end of the fiscal year.

Republicans have set concessions on healthcare as a price for lifting the current $16.7 trillion (£10.9 trillion) debt ceiling, without which the US will default on its debts by the middle of this month.

They appeared unmoved by the impact on the 800,000 US public-sector workers who have now been put on unpaid leave or the million who are being asked to work for free.

"Unfortunately, Congress has not fulfilled its responsibility," Mr Obama said in a letter to employers.

"It has failed to pass a budget and as a result, much of our government must now shut down until Congress funds it again."

Troops in Afghanistan and elsewhere will stay on duty, he said, noting he'd signed a law to ensure they got their pay cheques on time.

But thousands of Defence Department civilians are among those who face a layoff.

Mr Obama said. "You and your families deserve better than the dysfunction we're seeing in Congress."

Some essential services, including air traffic control and social security benefits, will continue to function.

But it is unclear how long the shutdown will last or how Congress will find a way to agree on restoring funding.

President Obama will meet top Wall Street bosses tomorrow to discuss the state of the economy.