Nairobi has the most English proficient speakers on the continent, according to a new study.

Nairobians' knowledge of spoken and written English, according to the English Proficiency Index 2019, is 61.94 per cent, the highest for any African city.

The EPI index, which ranked 100 countries and regions, reported that only two African cities -- Nairobi and Lagos -- which scored 58.47 are in the high proficiency band. About 13 African countries participated in the survey.

Globally, Kenya's English language skills ranked 18th, the second highest on the continent, after South Africa that ranked sixth in the world.

Nigeria and Ethiopia ranked 29th and 63rd respectively while Libya ranked the lowest.

The 2019 index saw eight new entrants in the survey, namely, Kenya, Sudan, Côte d'Ivoire, Bahrain, Kyrgyzstan, Maldives, Nepal and Paraguay.

Africa's average proficiency score dropped, primarily due to score changes in South Africa and Ethiopia and to the inclusion of Sudan and Cameroon, which both fall in the "very low" proficiency band, the report said.

Another key finding of the report was that the English proficiency gender gap is closing. In 2018, women's average English level was higher than men's worldwide and in a majority of countries. But in 2019, women outscored men by less than one point in Africa, Asia and Europe

The scores are achieved through analysing results from 2.3 million adults who took an online English test in 2018 via EF Standard English Test.

Authors of the EPI report also found a correlation between high English proficiency and various indicators of economic competitiveness, including higher income and increased labour productivity.

While there's no evidence that English proficiency directly drives economic success, the authors of the report say that the complex relationship between language skills and economic growth is that greater wealth facilitates more English training, and English skills help economies stay competitive hence highlighting the role that English plays in broader schemes for economic growth.

"We consistently find a correlation between ease of doing business and a country's English proficiency," said Kate Bell, a co-author of the survey.

The study further found a correlation between English proficiency and a country's service exports as well as the value added per worker in services.

As the complexity and sophistication of economic exchange increases, so does the demand for linguistic competencies, the survey explained.

The report notes that in the last 30 years, many emerging economies closed the gap with richer countries, thanks to manufacturing.

But as opportunities, especially in the manufacturing sector dry up, people will need to focus more on education, for both children and adults, to enable them tap into international trading opportunities and develop service-sector industries.