A judge has put a temporary halt to Nokia Siemens Networks’ acquisition of Motorola’s networks business after Huawei sued to stop the $1.2 billion deal, alleging it would result in the release of confidential trade secrets.

After a hearing Monday, Judge Sharon Johnson Coleman ordered that Motorola not disclose any of Huawei’s confidential information to Nokia Siemens Networks.

“Defendants Motorola, Inc., Motorola Solutions, Inc., and Motorola Mobility Holdings, Inc. (“Motorola”) are hereby ordered not to disclose any of Plaintiff’s confidential information to Defendants Nokia Siemens Networks US LLC and Nokia Siemens Networks B.V. (“NSN”),” Coleman wrote in her decision.

The ruling does not stop Nokia Siemens from completing the purchase of Motorola’s networks business but could complicate the deal’s closing.

The judge also ordered Motorola and Nokia Siemens to notify both Huawei and the court if China’s Ministry of Commerce, which is currently reviewing the acquisition, makes any decision on the deal.

Motorola said Monday that it believed Huawei’s lawsuit was “without merit” and maintained that the Nokia Siemens buyout would proceed on schedule. “As previously stated, we are targeting to complete the sale of our Networks business to NSN in early 2011 following receipt of approval from China’s antitrust authorities,” a Motorola spokeswoman said in a prepared statement.