David Cameron's extensions to GP hours have been praised by NHS England, but a British Medical Association committee chair has said the changes must be properly supported.
NHS England CEO Simon Stevens said the initiative could also free up time for GPs to spend with their sickest patients, giving it "the potential to be a win-win-win for patients, their doctors and the NHS".
But Dr Chaand Nagpaul, chair of the British Medical Association's General Practice Committee, said a more holistic approach was needed "so that community, social and urgent care work in tandem".
He also said ministers must "deliver on their commitment to increase resources in the community," so that GPs can be properly supported.
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Mr Kim has made two recent visits to China.
The study looked at the development of 422 children over the course of eight years.
The president said they will come into force if China refuses to change its practices.