Workers on London's Underground rail network have rejected a bonus offer covering the Olympics, raising fears that services could be disrupted during the Games this year.

The RMT union said the offer from management at publicly owned London Underground had too many strings and caveats attached to it.

Public transport is at the centre of the travel plans for the July 27-August 12 Games and there are fears that London's crowded and ageing networks will struggle to cope with the additional demand.

It is well documented that transport will be the biggest logistical challenge throughout the Olympics period with massive pressure on staff and services from moving millions of extra passenger journeys around Greater London and the South East, said RMT General Secretary Bob Crow.

All we are calling for is a fair deal for all the staff involved in delivering the colossal transport challenge that we will be facing this summer and the negotiations to achieve that are ongoing..

The RMT said the offer consisted of a 100-pound bonus dependent on meeting certain customer satisfaction targets, plus an additional 20 pounds per shift during the Olympics and Paralympics.

(Reporting by Keith Weir; Editing by Clare Fallon)