David Cameron, who has notoriously poor schoolboy French, is urging today's youngsters to abandon the language of Molière and Voltaire to concentrate on the tongue of the future – Mandarin.

In a parting shot, as he left China after a three-day visit, the prime minister said that pupils should look beyond the traditional French and German lessons and instead focus on China.

To reinforce his message the prime minister quoted Nelson Mandela, who said learning someone else's language is the best way to their heart. Cameron said: "I want Britain linked up to the world's fast-growing economies. And that includes our young people learning the languages to seal tomorrow's business deals.

"By the time the children born today leave school, China is set to be the world's largest economy. So it's time to look beyond the traditional focus on French and German and get many more children learning Mandarin.

"As Mandela once said: 'If you talk to a man in a language he understands that goes to his head, if you talk to him in his own language that goes to his heart.'"

Cameron, who visited a school for six- and seven-year-olds learning English in Chengdu, said that a partnership between the British Council and Hanban – the Chinese National Office for Teaching Chinese as a Foreign Language – will double the number of Chinese language assistants in the UK by 2016 and provide increased funding to lower the cost to schools of offering Mandarin as a language option.

In an expansion of the UK-China School Partnerships programme, funding will also be provided for 60 headteachers to make study visits to China in 2014.

The announcement was welcomed by the British Council and the British Academy, both of which have been pushing for policies to reverse the decline in students taking modern languages at school and university level.

Martin Davidson, the British Council's chief executive who has been visiting China with Cameron, said: "The promotion of Chinese language in the UK and the English language in China are both vital to economic and cultural relations between the two countries. This initiative will increase collaboration and is particularly significant given that recent British Council research shows that Mandarin is one of 10 languages not widely spoken in the UK and yet crucial to our future growth and prosperity."

In recent research the British Council placed Mandarin in the top five most important languages for Britain's future prosperity, security and influence. But it found only 1% of the adult population speaks Mandarin to a level that allows them to conduct a basic conversation. Just 3,000 pupils in England, Wales and Northern Ireland entered for Chinese languages GCSEs in 2013, putting it far behind the traditional choices of French with 177,000, Spanish with 91,000 and German with 62,000 entrants, as well as Urdu, Polish and Arabic.

But the popularity of Chinese languages improves at A-level, where it was the fourth most popular modern language in 2013, with 3,300 entrants compared with 11,000 taking A-level French and 4,200 taking German.

The estimated 500,000 ethnic Chinese living in Britain make it the largest overseas Chinese population of any European country.

Professor Dame Helen Wallace, the British Academy's foreign secretary, said her organisation had been arguing for an improvement in foreign language skills, and had identified Mandarin as one of the extended range of languages to be promoted in schools.

But a lack of qualified teachers could be a barrier to improving its popularity, Wallace said.

"The supply chain needs to work in both ways. Children need to be persuaded to do it and you need the availability of capable teachers at all levels – primary, secondary and university – to develop positive reinforcement in the availability of teachers and the interest of teachers."

And she warned: "No such strategy works unless you stick at it. There's no use doing this for two or three years and then forgetting about it – you have to make a long-term investment in this kind of change capacity."Laura Chan, one of the co-founders of the Marco Polo Academy, a bilingual Mandarin-English primary school opening in Barnet next September as part of the free schools programme, said the prime minister's announcement was good news for the status of Mandarin.

"It's a great help. It will increase people's awareness of Mandarin as a language they can learn," she said.

"One reason we wanted to set up the free school is that the teaching of language in the UK is not particularly effective, especially for young children."

From September 2014, studying foreign languages will be compulsory in primary schools under the new national curriculum.