The government has been warned it must do more to prepare the NHS for next year's changes in GPs' working hours.

In a new report released on Friday the Commons health select committee said the opt out from providing out-of-hours services which comes into effect on December 31 has not been fully thought through.

The MPs found that primary care trusts are "in varying states of readiness" for the change - which will allow family doctors not to work nights or weekends.

Around nine out of 10 GPs are expected to take up the opportunity.

The cross-party committee also warned that more funding may be required to cover the gap in the provision of services which will open as the changes come into effect during 2005.