Updated 08:43

US lawmakers have failed to avert a partial shutdown of government services after a deadline to agree how federal money should be spent passed without agreement.

The Democrat-dominated Senate and Republican-controlled House of Representatives refused to back down in a clash over President Barack Obama's controversial healthcare law, known as Obamacare.

The deadlock means non-essential services, including some of America's most famous tourist attractions, will be forced to close, while hundreds of thousands of workers face the prospect of unpaid leave. 

These Americans are frustrated:

It is the first US shutdown in 17 years, with analysts concerned about its potential impact on Wall Street and other global markets.

The military's 1.4 million active duty personnel would remain on duty, although their pay cheques will be delayed. 

Obama addressed his troops shortly after the shutdown began:

While last night, before the outcome became obvious, he warned of the serious consequences of a shutdown.

The Internal Revenue Service will suspend audits and taxpayer services, programmes for children will be halted and up to 800,000 government employees will be forced to take temporary leave, possibly without pay.

Due to a lapse in government funding, this account will not be active until further notice.

— U.S. Capitol (@uscapitol) October 1, 2013

Mr Obama's healthcare law was passed by Congress and signed into law in 2010, despite opposition by the Republican Party, especially Tea Party conservatives.

However, the scheme, which aims to provide greater access to affordable health insurance for poorer sections of society, has yet to be funded.

In March, the Republicans and Democrats failed to agree on a 2013/14 budget bill that would have funded Obamacare, although they reached a compromise that gave both sides an extra six months - until October 1 - to continue negotiations.

The Dow Jones index closed 129 points down on deadline day, a fall of nearly 1%.

In Japan, the Nikkei closed 2% lower, while in Britain, the FTSE 100 was almost 1% down.