British bosses saw their pay increase by 18 per cent last year, according to a survey of 1,000 directors, but female executives are still lagging behind their male counterparts.
The research from Incomes Data Services annual boardroom survey found almost half now earned more than £1 million, with eight receiving packages worth in excess of £5 million.
Its survey has come as a study by the Institute of Directors and consultancy Croner has suggested that, despite more women reaching the top rung of the corporate ladder, they still earn, on average, almost a quarter less than men.. IDS has assessed executive pay for the past 15 years, and this time round said it had never seen so many earn so much money
The rise in directors' wages compared with average settlements of between three per cent and 3.5 per cent in the wider economy, it added.
The finding has been slammed by the TUC, which called the increases "sky high".
General secretary Brendan Barber said: "Whilst ordinary workers are happy to accept pay rises in the region of 3.5 per cent, the bosses of the UK's top 350 companies are rewarding themselves pay increases that are almost six times bigger.
"Some shareholders are trying to keep a lid on executive pay, but these figures suggest that remuneration committees are still finding ways of inflating the overall reward package," he added.
Shareholders needed to "pay more attention to the total amount paid out to directors and concern themselves more with the gulf opening up between top bosses' pay and that of the rest of the workforce", he warned.
"Otherwise we'll continue to see these huge increases in directors' pay year on year," he added.
The IoD survey calculated that a female director now earns an average of £55,000 per annum compared with the average male executive's basic pay of £72,100.
In a further knock to the image of the City of London, the biggest pay gap occurs in the Financial Services Sector where women bosses earn 35 per cent less than their male counterparts, it added.
The public sector had the smallest gender pay gap at 7 per cent, and also had the highest proportion of female directors, 21 per cent.
Miles Templeman, IoD director general, said: "Although we are, fortunately, seeing more and more women reaching board level within organisations, the rewards of accomplishing that feat are still being distributed unevenly.
"If the jobs are the same clearly the pay should be equal. Talent and hard work have to be paid for regardless of gender," he added.
Back in September, research from Deloitte suggested UK bosses were now commonly enjoying bonuses worth 100 per cent of their salaries, with some getting as much as 150 per cent.
But Deloitte also found basic salaries for executive directors were increasingly more slowly than in the past, with those in the FTSE 350 going up 6.5 per cent compared to 7.1 per cent in 2004 and 7.5 per cent in 2003.