Thousands of passengers using London's train, buses and Underground system travelled for free on Saturday after a technical glitch brought down its Oyster card network.

Staff opened barriers at rail and tube stations and bus drivers waved on passengers after the card 'reader' machines used by commuters to register their journeys failed.

"We're experiencing technical issues with our Oyster Card readers this morning where customers are unable to touch in or out," said a message on Transport for London's official Twitter page.

"We're working on a fix and customers are being allowed to travel across Tube/Bus/Rail networks," it added.