According to INRIX's 2015 Traffic Scorecard, motorists in London wasted more than 100 hours in gridlock last year.
This figure, which was the result of analysis of traffic congestion in more than 100 cities worldwide, contributed to a UK average of 30 hours spent in delays, Fleet News reports.
London topped the list of congested cities, with motorists wasting an average of 101 hours. This equates to more than four days spent in gridlock in 2015.
The average amount spent in delays across the UK remained consistent with 2014, with drivers spending an average of 30 hours in congestion.
As a result of Switzerland's rise in traffic levels, the UK dropped to sixth place in the European ranking. Belgium remains the most gridlocked country, with an average of 44 hours.
UK metropolitan areas saw a slight increase in congestion in 11 out of the 18 areas in 2015, compared to 14 in 2014.
Outside of London, Belfast saw the biggest increase, with an average of 38 hours, while Birmingham saw the biggest decline with a fall of 2.5 hours to 34 hours annually.
The UK's ten most congested metropolitan areas were the London Commute Zone, Greater Manchester, Greater Belfast, Merseyside, South Nottinghamshire, Birmingham/Black Country, Avon & North Somerset, Leeds-Bradford, Coventry & Warwick and South Yorkshire.
"London is the victim of its own success, with a robust jobs market and a growing economy attracting more people, more construction and consequently more traffic," said Bryan Mistele, president and CEO of INRIX.
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