(Reuters) - The "Big Four" accounting firms have said they intend to appeal against a ruling by the U.S. Securities and Exchange Commission (SEC) that recommends suspending their Chinese units for six months.

In a joint statement, Deloitte, Ernst & Young, KPMG and PricewaterhouseCoopers stressed that the decision was not final or legally effective until it has been fully reviewed and approved by the SEC.

"The firms intend to appeal and thereby initiate that review without delay," the statement said.

"In the meantime, the firms can and will continue to serve all their clients without interruption," it continued.

The statement follows a 112-page ruling by an SEC judge that has escalated the long-running dispute between U.S. and Chinese regulators over access to audit documents.