Labour's pledge to introduce a cap on rent prices is a "ridiculous thing to suggest" as it will drive down the quality of property available, according to the Housing Minister.
Kris Hopkins warned "investment and quality" of rented properties had "always fallen" when a cap on the amount of money private landlords could charge was introduced.
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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.