President Barack Obama met with congressional leaders for an hour late on Wednesday but his Democrats and rival Republicans refused to concede on budgetary issues that have partially shut down federal services.

Senate Democratic leader Harry Reid emerged from the talks saying congressional Democrats would never allow Republicans to overturn Obama's health care law.

"We are locked in tight on Obamacare," Reid said, adding that neither the president nor Democrats would accept changes to the health care reform that Obama regards as a key outcome of his presidency.

Republican House Speaker John Boehner said the president had "reiterated one more time that he will not negotiate."

Also present at the talks had been the Senate Republican leader Mitch McConnell and House Democratic leader Nancy Pelosi.

House Republicans are demanding that Obama agree to cut funding or delay implementation of his healthcare law in exchange for their approving spending measures to reopen federal government services.

In addition, the US faces a historic debt default on October 17 unless Congress agrees to raise the US borrowing limit.

The impasse leaves the federal government without a budget for the new fiscal year.

Executives also met Obama

Chief executives of large US firms met Obama for more than an hour earlier on Wednesday.

One of them, Lloyd Blankfein of Goldman Sachs said threats should not be used as a "cudgel" to cause the US to fail on its obligations to repay its debts.

'Extremists' and 'extortion'

In an interview with CNBC, Obama said he would not negotiate with Republicans until government was reopened.

"If we get in the habit where a few folks, an extremist wing of one party, whether it's Democrat or Republican, are allowed to extort concessions based on a threat (to) undermine the full faith and credit of the United States, then any president who comes after me, not just me, will find themselves unable to govern effectively," Obama said.

The partial shutdown, which began on Tuesday, has closed iconic US national parks and monuments, frustrating holidaymakers and tourists, and forced 800,000 employees, nearly a third of the federal workforce, off the job on unpaid leave.

Staff classified as essential such as air traffic controllers, Border Patrol agents and most food inspectors continue to work.

European Central Bank chief Mario Draghi warned that the US shutdown was a risk "if it is protracted."

The stand-off has caused Obama to shorten a long-planned Asia trip that he was due to begin this weekend. In doubt are stopovers in Malaysia and the Philippines.

ipj/jm (Reuters, AP, AFP)