The average annual pay package for a FTSE 100 CEO is £4.5m and may rise by a third this year, according to a think tank.
The High Pay Centre (HPC) said by the end of 2014 the average remuneration could be £6m - undermining the Government's attempt to thwart runaway executive pay.
The HPC said the average pay for top bosses was £4.3m in 2012 before rising on average £200,000 last year.
It said last year's average pay of £4.5m could rise another 33% by December.
Several major companies have seen significant rebellions on pay recently.
But shareholders have not gone as far as voting down either individual pay packages or future pay policy.
HPC said "many companies are flouting new regulations" on comparative analysis of CEO pay to other workers in their firms.
It said they were "exploiting a clause" enabling a smaller comparator groups that can represent less than 1% of their employees.
High Pay Centre director Deborah Hargreaves said: "These figures show that the new regulations are not enough to bring top pay back to a level that is sensible, fair or proportionate.
"Over the past 15 years, pay for a FTSE 100 CEO has gone from being 60 times the average UK worker to 160 times, without any justification.
"All workers should share in a company's success - our economy cannot succeed in the long-term if a tiny group at the top pull further and further away from everybody else."
The HPC has argued that ordinary employees should be represented on remuneration committees that set pay packages for executives.
Its analysis of FTSE 100 companies covers those whose most recent financial year ended in the last quarter of 2013.
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