Companies should have two auditors to check their books, MEPs have suggested in a move that seeks to strengthen proposals to increase competition and reform the audit market.

The moves came just days after a group of large institutional investors and associations representing some €732bn (£590bn) of funds, urged European legislators to strengthen proposals to reform the audit market by backing auditor rotation every 15 years and restricting non-audit work for audit clients to 50% of the audit fee.

Their urgent requests came after original plans had been watered down.

The latest push towards joint audits is a significant addition to a draft EU law aimed at improving the performance of auditors blamed for giving banks a clean bill of health just before they were bailed out by taxpayers in the 2007-09 credit crunch.

The shake-up is also part of a wider drive to halt the dominance of the 'Big Four' firms - KPMG, PricewaterhouseCoopers, Ernst & Young, and Deloitte.

But smaller auditors believe a system of shared audits - where the junior partner checks the books of a subsidiary - is a more likely outcome.

Assembly lawmakers from the centre right and socialists, said they supported joint audits for listed companies, so players such as BDO, Mazars or Grant Thornton, could partner up with a Big Four player to sign off accounts.

Angelika Niebler, a German centre right member, said the EU must be 'more courageous' in breaking up the Big Four's stranglehold, Reuters reports.

Spanish centre-left member, Antonio Masip Hidalgo, said he would bring forward amendments to make the law 'more reformist' by including joint audits.

Both the German and Spanish parties have sufficient votes between them to drive through the relevant amendments but the final draft will also need the wider backing of member states.

They expressed their views as a direct response to an attempt by British Conservative MEP Sajjad Karim - the rapporteur for the European Parliament's Legal Affairs committee - to dramatically dilute calls to make auditor rotation for public interest entities compulsory every six years. Karim recommended a change of firm every quarter century.

He said that he proposed such a long timeframe because issues of unfair competition should be handled by competition authorities and not lawmakers.

Karim's amendments have also done away with submissions to encourage the use of joint audits for public-interest entities to reinforce professional scepticism and improve audit quality.

Smaller auditors insist that EU or UK regulatory intervention would improve the chances of more work and thereby underpin further investment in more accountants.

The Big Four meanwhile, insist changes are already happening and that days of a company staying with the same firm for generations are history.