Company bosses were paid an average of 129 times more than their employees in 2015
The report found that the average pay of a FTSE 100 CEO was 129 times greater than that of their employees in 2015.
The median pay packet of just under £4 million is 144 times that of the average Briton, which is around £28,000.
Stefan Stern, director of the High Pay Centre, said: "There is apparently no end yet in sight to the rise and rise of FTSE100 CEO pay packages. In spite of the occasional flurry from more active shareholders, boards continue to award ever larger amounts of pay to their most senior executives."
Prime Minister Theresa May said last month that there "is an irrational, unhealthy and growing gap between what these companies pay their workers and what they pay their bosses."
May has proposed that companies should be obliged to disclose average pay ratio between CEOs and employees, as well as consulting an "ordinary employee" when setting levels of executive pay.
CEO pay rose 10% in 2015 from an average of £5 million in 2014, and is up from £4.1 million in 2010. The highest paid CEO was Martin Sorrell of WPP, who earned £70.4 million in 2015, up from £43 million the year before.