President Xi Jinping has said China needs at least 6.5 per cent economic growth in coming years to become "moderately prosperous".

The ruling Communist Party also announced plans to let the country's tightly-controlled currency trade freely by 2020.

The announcements follow a high-level planning meeting last week at which party leaders promised to make the world's second-largest economy more productive and to raise living standards.

Mr Xi said growth of "no less than 6.5 per cent" is required to achieve the party's goal of doubling the economy's size by 2020 from its 2010 level.

Chinese growth has slowed steadily over the past five years as the ruling party tried to steer the economy to a more sustainable expansion based on domestic consumption instead of trade and investment.

An abrupt decline over the past year prompted Beijing to try to shore up growth by cutting interest rates six times since last November.

Mr Xi's comment was the latest indication the party might reduce its official growth target, which has stood at 7 per cent since 2011. Last year's economic growth was 7.4 per cent and this year it is expected at just below 7 per cent.

Private sector analysts have warned sticking to a high target could conflict with official efforts to shift China to more sustainable growth based on domestic consumption instead of trade and investment.

Some say a more realistic level would be 5.5 to 6 per cent, which would still rank China among the fastest-growing major countries.

Mr Xi said "maintaining a medium-high level of growth" was required for "comprehensively building a moderately prosperous society".

China's GDP per head is about £5,190 compared with £35,600 for the US and £23,300 in Japan.

Last week, the ruling party eased its birth limits to allow all couples to have two children in a response to the need for more young workers in a rapidly ageing society.

The party also said its leaders agreed last week to make the yuan a "freely tradable and freely usable currency" by the end of their next five-year development plan in 2020.

The US and other governments have pressed Beijing for years to end controls they complained kept the yuan undervalued, giving Chinese exporters an unfair price advantage. Some American politicians had demanded punitive tariffs on Chinese goods in retaliation.

Beijing has been gradually expanding use of the yuan abroad for trade but restricts the daily movement of its exchange rate and the flow of money into and out of China.