The UK is set to become the best-performing economy in western Europe next year, and is likely to overtake powerhouses Germany and Japan in the 2030s, a report says.
The World Economic League Table from think tank the Centre for Economics and Business Research (Cebr), said the UK's rise up the world rankings would be due to the strength of its IT and software industries as well as its culturally diverse workforce.
The UK is currently the fifth-largest economy in the world, with a gross domestic product (GDP) worth $US3 trillion ($A4 trillion) this year, behind Germany at $US3.3 trillion, and Japan in third spot at $US4.1 trillion.
The US remains the richest country in the world with a GDP worth $US18 trillion, followed by China at $US11.4 trillion
However, during the 2030s, the report said, the UK was likely to be overtaken by Brazil, currently worth $US1.8 trillion.
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It also warned of risks to the UK economy.
"Its weakness is its bad export position and unbalanced economy, with many parts of the country heavily dependent on subsidies from the relatively high taxes levied on Londoners," it said, adding the possibility of Scotland, or even Northern Ireland, seceding from the union would hurt growth.
The UK's referendum next year on its continuing membership of the European Union might lead to a more insular culture, which would also generate slower economic expansion, it said.
A UK government spokesman said: "The UK is now set to be the best-performing economy in western Europe and it could overtake Japan in the 2030s and then Germany.
"With the deficit reduced by almost two thirds as a share of GDP since its peak in 2009-10, an average of 1000 extra people in work each day and employment rates at a record high, the Government's plan for a more prosperous future is delivering for working people."
Due to slower Chinese economic growth and a weaker currency, the Cebr has pushed back last year's forecast of when the Asian nation will overtake the US to become the world's richest country by four years to 2029.
