Jan 5 (Reuters) - A federal judge on Thursday ordered a Chinese unit of Deloitte & Touche to appear in court and defend itself against efforts by U.S. regulators to obtain documents related to possible accounting fraud.

Deborah Robinson, a magistrate judge in Washington, ordered Deloitte to appear in court on Feb. 1 and explain why the court should not force it to turn documents over to the U.S. Securities and Exchange Commission.

The SEC put that request to the court in September, after Deloitte failed to respond to a subpoena seeking information about its Chinese unit's audits of Longtop Financial Technologies Ltd, a Chinese company under investigation by the SEC.

Dozens of China-based companies have disclosed auditor resignations and book-keeping irregularities in the past year, prompting a broad SEC and Justice Department review into accounting fraud at Chinese companies listed on U.S. stock exchanges.

But investigators face difficulties in obtaining documents and evidence from auditors in China.

In October the judge put the brakes on the SEC's request about Deloitte, and asked why the agency was not going through procedures set up by the Hague Convention to access that information.

The SEC's request to the court was complicated by Deloitte's position in the case; its lawyers have not formally acknowledged to the court that they are representing the firm.

On Wednesday afternoon, Robinson issued an order agreeing with the SEC that the court had the authority to move forward even without any acknowledgement from Deloitte's lawyers that they had received the SEC's application.

In her Thursday order, Robinson set a schedule for both sides to lay out their arguments in advance of a February hearing.

A lawyer for Deloitte did not immediately respond to a request for a comment.

(Reporting By Aruna Viswanatha)

Follow us on Twitter: @ReutersLegal