Britain stepped up its fight against unacceptable bank bonuses on Tuesday by proposing improved disclosure on pay from next year, backed by shareholders also angered by the scale of rewards.

The government, which struck a deal with British banks earlier this year to rein in pay and lend more, is set to pile on further pressure after launching a consultation on better transparency around bonuses.

Its plan would require 15 lenders -- not just British banks but the UK operations of large foreign banks -- to make public the reward packages for the eight highest-paid non-board executives.

That would mean top traders and deal advisers would have their pay disclosed, but they would not be named. The measures would kick in next year, to include the 2011 bonus round, already under scrutiny from investors and politicians.

We want shareholders to hold banks to account for their bonus structure, which is why we're taking action to make top-level pay more transparent, said Mark Hoban, Financial Secretary to the British Treasury.

Banks already have to disclose the five highest-paid non-board executives and similar transparency rules are in place elsewhere, meaning lenders in the European Economic Area will be exempt, even though many have big investment banking operations in London.

But those affected could include big U.S. investment banks such as Goldman Sachs and Morgan Stanley. The disclosure demands also go further than elsewhere by requiring rewards to be split up into fixed, variable and deferred pay and other components.

Britain's crackdown on bonuses comes as politicians in the UK and across Europe bear down on banker pay again, not least because of the increased capital demands lenders are facing in the face of a raging euro zone crisis.

Calls to slash payouts and dividends to shore up capital have grown in recent weeks, and shareholders, keen to make sure the pain is shared with the banks, are wading in to support a pay overhaul.

Britain's Association of British Insurers, whose members own about a fifth of Britain's publically traded shares, called for rewards to be slashed on Monday, pointing to tumbling share prices and capital demands.

It is our members' view that it can no longer be business as usual for this remuneration round, ABI director general Otto Thoresen wrote in a letter to the country's top banks.

Any capital retention should not be solely funded by a reduced payment of dividends, Thoresen said.

THE BACKLASH BEGINS

Shareholders' anger over bankers' pay has usually been vented by voting against remuneration proposals, and this year Britain's HSBC faced a backlash over its reward plans.

But anger over bonuses looks set to spiral again ahead of the New Year bonus season, even if European banks have so far put less aside to pay their staff than they had this time last year.

Most still notched up bonus pots even in a dismal third quarter and the fall in revenues -- down 30 percent in the three months to September at the top 10 investment banks globally, according to research group Coalition -- largely outstripped the drop in compensation.

Even in France, where even the top banks are not known for paying out the very high individual rewards more common in the City of London, politicians are calling on banks to cut back on bonuses.

Prime Minister Francois Fillon met with top executives at the likes of BNP Paribas and Societe Generale last month to tell them to keep lending to the French economy while keeping a lid on bonuses.

One participant at the meeting said there was no objection from bankers, who were in similar hot water over compensation during the last crisis.

In Britain, fresh calls to cut bonuses and dividends further came this week from Bank of England governor Mervyn King and deputy prime minister Nick Clegg.

Only part nationalised Royal Bank of Scotland did not accumulate any fresh rewards in the third quarter, and bonuses accrued so far this year stand at roughly 416 million pounds ($653.45 million), based on company reports.

These were down over 56 percent on what it had notched up to hand out to staff for the whole of 2010. Overall, British banking bonuses could drop by nearly 40 percent.

(Additional reporting by Myles Neligan in London and Lionel Laurent in Paris; Editing by Hans-Juergen Peters, Sinead Cruise and Helen Massy-Beresford)