William Parrett, global chief executive of Deloitte, is candid enough to admit that the big accounting firm has not yet achieved the level of excellence he wants.

Deloitte's strategy for the next 10 years carries the slogan "to be the standard of excellence".

He wants Deloitte to stand for "a top-quality audit" and to become one of the world's "remarkable brands". He says the firm should be the choice of "the most sought-after client . . . and the most sought-after talent".

However, the "standard of excellence" slogan risks making Deloitte a hostage to fortune if, like other top accounting firms, it continues to be accused of poor auditing. Deloitte's Italian business, for example, is under criminal investigation over its auditing at Parmalat, the dairy group that collapsed amid accounting fraud in 2003.

Parrett, recognising the increasing expectations for auditors to spot accounting frauds quickly, says: "We are trying to do a better job in catching and reducing the number of frauds."

Deloitte's new strategy is based on a year-long review that concluded it should remain a multidisciplinary organisation. The big four accounting firms - Deloitte, Ernst & Young, KPMG and PwC - all insist they must retain multidisciplinary capabilities in order to do good auditing. However, Deloitte is unique among the big four in deciding to retain its consulting business, which supplies companies with computer systems for financial reporting and risk management. The other firms sold off their consulting practices because of concerns by regulators about conflicts of interest. But Deloitte, having toyed with following suit, pulled back.

Deloitte's strategy says its core businesses will be "audit, tax, consulting and financial advisory services". The consulting practice generated global revenues of $4.3 billion (€3.6 billion) in Deloitte's 2005 fiscal year, and Parrett highlights how it is enjoying growth after two years of decline.

The strategy also confirms that Deloitte, like the other big accounting firms, will focus on expanding its presence in China and India. Deloitte's member partnerships in Asia continue to be its fastest-growing.

But perhaps the most interesting part of Deloitte's strategy is its statement about the firm's structure. The firm says its 80 member partnerships may be reduced through consolidation, although it will continue to cover 150 countries.

That consolidation might herald a far bigger event: the formation of a single global partnership. Although Deloitte's strategy does not refer to proposals to create one, Parrett says he expects the big firms to transform themselves into single partnerships over the next decade. He believes regulators, who have concerns about inconsistent audit work by the firms across countries, will probably press for the changes.

Parrett is the second leader of a big four firm to make the prediction about single global partnerships. Michael Rake, global chairman of KPMG, said last year the firms could make such changes over the next 10 years.

Parrett sees no contradiction between the statement in Deloitte's strategy that the interests of its member businesses are best served by its existing federation-style structure, and his prediction of a single global partnership within a decade.

He highlights how laws in many countries ban accounting firms from turning themselves into single partnerships.

The big firms therefore organise themselves as networks of member businesses, which means that their global leaders have limited authority. If the firms were single global partnerships, their leaders would have greater powers to ensure auditors did consistent and high-quality work.

Meanwhile, Deloitte's strategy does not involve trying to replace PwC as the world's biggest firm over the next decade. Deloitte has already achieved its 1998 target of becoming the world's second biggest firm.