Accountancy giants have called for greater clarity in the tax system as they responded to government proposals to clamp down on firms which sell tax avoidance schemes to businesses.

The treasury said accountants who help wealthy individuals and companies unlawfully exploit tax rules could be forced to pay fines of up to 100% of the tax that was underpaid, while banks which profit could also be targeted.

Accountants currently face little risk when selling schemes while their clients can be forced to pay penalties if successfully prosecuted by HM Revenue and Customs (HMRC) in court.

The 'Big Four' accountancy firms were attacked by the House of Commons Public Accounts Committee last year for making lucrative profits out of designing and selling ways for their clients to avoid tax.

In response to the plans, KPMG said 'times have changed' and that 'what was seen as acceptable behaviour is no longer regarded as appropriate'.

'We recognise that there's a potential conflict between a taxpayer's right to minimise their tax liability and the duty they have to society to pay a fair amount of tax. We think about and treat this very seriously and have codified our approach,' said a spokesman.

But PwC warned that any new measures should not impact its ability to give advice to clients.

Kevin Nicholson, head of tax at PwC, said: 'We support the efforts to ensure there is greater clarity in this area.

'Any new measures that are introduced must be appropriately targeted and proportionate so that the ability of taxpayers to receive independent professional advice is not adversely impacted.'

EY said it supports 'improving certainty and transparency in the tax system and compliance with it'.

Deloitte did not respond to request for comment.

Do you have a business story? Email mark.shields@archant.co.uk or call 01603 772426.