US President Barack Obama has begun talks with congressional leaders at the White House over the US government shutdown.

Mr Obama is meeting House of Representatives Speaker John Boehner, Senate Majority Leader Harry Reid, Senate Republican leader Mitch McConnell and House Democratic leader Nancy Pelosi.

Hundreds of thousands of federal employees have been forced out of work by the shutdown.

Police cordoned off landmarks, including the Lincoln Memorial, and government agencies stopped cancer treatments and trade negotiations.

Republicans in the House of Representatives have moved to restore funding to national parks, veterans' care and the District of Columbia.

The stand-off has raised new concerns about Congress's ability to perform its most basic duties.

An even bigger battle looms as Congress must raise the debt limit in coming weeks or risk a US default that could cause havoc with global markets.