The BDO network of accounting firms said Tuesday that annual revenue grew 6.11 percent worldwide for its member firms compared to last year.

For the year ending Sept. 30, 2012, revenue for all BDO member firms, including the members of BDO’s Member Firms’ Alliances, totaled $6.015 billion.

Revenue from assurance services accounted for 61 percent of combined fee income, followed by tax services representing 18 percent and advisory services 21 percent. BDO’s network encompasses 54,933 total staff members spread across 1,204 offices in 138 countries.

“Companies all over the world are fiercely focused on cost, value and above all, service. The continuing positive results of our member firms is a testament to BDO’s dedication to exceptional client service,” said BDO International CEO Martin van Roekel in a statement. “BDO is the leading brand for companies operating in the mid-market and it is therefore no great surprise that we are attractive to both independent firms and those within other networks. BDO stands for exceptional client service, delivered by exceptional people, and they want to be part of that.”

The Asia Pacific region was the fastest growing part of the world for BDO, with an increase in combined fee income of 48 percent. This was followed by strong growth in the Middle East region of 32 percent and a double-digit increase in North America and the Caribbean. Sub-Saharan Africa saw an 8.4 percent increase and Europe a 4.6 percent increase.