LONDON (Reuters) - More than a fifth of Britain's biggest companies have been named on a register ordered by Prime Minister Theresa May to highlight shareholder concern at "fat cat" pay, including WPP (>> WPP Group), Sky (>> Sky), Burberry (>> Burberry Group) and AstraZeneca (>> AstraZeneca).

The list, compiled by the Investment Association, is part of a package of corporate governance reforms set out in August that May said would tackle the "unacceptable face of capitalism", such as pay rises for bosses that far outstripped company performance.

The data published on Tuesday shows that 22 percent of companies listed on the FTSE All Share index had at least one resolution that received more than 20 percent opposition at shareholder meetings, or was withdrawn, the Association said.

Association CEO Chris Cummings said the register revealed the true scale of investor concern and showed shareholders flexing their muscles by exercising their votes.

"With over one-fifth of the FTSE All-Share having faced large shareholder opposition in 2017, a significant number of companies need to seriously start listening to shareholder views and acting on them," he said.

Sky, Burberry, Morrisons (>> Wm Morrison Supermarkets), WPP and AstraZeneca were among the firms that saw more than 20 percent shareholders oppose their remuneration reports this year - with revolts ranging from 21 percent at ad group WPP to 48 percent at supermarket Morrisons.

(Reporting by Paul Sandle; editing by Stephen Addison)

Stocks treated in this article : AstraZeneca, Burberry Group, Wm Morrison Supermarkets, Sky, WPP Group