UPDATE 2-Aviva hit by boardroom pay backlash

* 50 percent vote against pay deal, 9 percent abstain

* Chairman apologises for not reflecting investor views

* Directors' performance "abject" - shareholder

By Myles Neligan

LONDON, May 3 (Reuters) - Half of insurer Aviva's shareholders voted against its executive pay plans on Thursday, one of the biggest revolts on remuneration ever suffered by a British company, underscoring growing investor hostility to excessive rewards for directors.

The dissenting vote, which compares with an average of just 6 percent in Britain last year, comes amid mounting determination in Europe that boardroom pay should match performance more closely as a sluggish economy crimps growth.

More than a third of Swiss bank UBS's shareholders on Thursday rejected its remuneration plans, mirroring investor rebellions last week at rival lenders Barclays and Credit Suisse.

Aviva shareholders attending its annual meeting in London protested that director pay at the insurer has continued to climb despite a persistently weak share price, and called for directors including Chief Executive Andrew Moss to quit.

"The figures are evidence enough to condemn your abject performance without reservation," said private investor Philip Meadowcroft, who estimated Aviva's total boardroom pay rose 90 percent between 2007 and 2011 while its shares fell 62 percent.

Aviva's outgoing chairman, Colin Sharman, apologised to investors and pledged to listen more closely to their concerns in future.

"We recognise a number of shareholders felt we have not reflected their views," he said.

"For that, the board and I apologise."

A further nine percent of votes on Aviva's remuneration report were withheld, leaving just 41 percent in favour. The vote is advisory only, and cannot block the insurers' pay plans.

Shareholder votes on pay would become legally binding under a set of draft legislation aimed at beefing up investor rights currently under discussion with industry.

"This is a further move from shareholders in their struggle for power with those running the companies they invest in," said Adrian Hoggarth of law firm Prolegal.

"Companies would be right to be nervous about the powers that shareholders may soon be granted."

Aviva, Britain's second-biggest insurer, had on Monday attempted to mollify angry investors by cancelling Andrew Moss's pay rise for 2012, and opening a review into its recruitment offers for top executives.

Last year, the company paid Trevor Matthews, the newly-appointed head of its UK division, 470,000 pounds ($761,500) in cash and over 2 million pounds' worth of shares as compensation for giving up benefits due under his previous employment.

Aviva is not reviewing overall pay levels for directors, but has said it will continue to discuss the issue with its owners.

Britain's biggest investor rebellion over pay was the 90 percent vote against Royal Bank of Scotland's remuneration report in 2009, widely seen as a protest against former chief executive Fred Goodwin's pension.

Sixty percent of shareholders in oil group Royal Dutch Shell voted against its executive pay plan the same year.

Also on Thursday, 37.4 percent of investors in British satellite company Inmarsat voted against its remuneration report.

Aviva shares closed little changed at 311 pence, valuing the company at about 9 billion pounds.