NEW YORK, July 26 (Reuters) - Former U.S. President Donald Trump"s billionaire ally Thomas Barrack pleaded not guilty on Monday to charges of illegal lobbying for the United Arab Emirates, putting the case on course for a possible trial. Barrack entered his plea to seven criminal counts before U.S. Magistrate Judge Sanket Bulsara in Brooklyn. The charges against Barrack, 74, included secretly lobbying the Trump administration for the UAE between 2016 and 2018, and lying to investigators about dealings with the Middle Eastern country. Barrack, who chaired Trump"s 2017 inaugural fund and was a frequent guest at the White House, was released last week on $250 million bond, secured by $5 million in cash as well as several properties and stock valued at $150 million. Bulsara said Barrack may live at his home in Aspen, Colorado while awaiting trial. The next hearing is scheduled for Sept. 2 before U.S. District Judge Brian Cogan. In an indictment unsealed last week, federal prosecutors accused three people - Barrack, his former employee Matthew Grimes, and an Emirati businessman - of failing to register as lobbyists, and using their influence to advance the UAE"s foreign policy in the United States. Grimes pleaded not guilty on Monday to conspiracy and illegal lobbying charges, and was released on $5 million bond. The third defendant is at large. Barrack founded the digital infrastructure-focused private equity firm DigitalBridge Group Inc (DBRG.N), known as Colony Capital Inc before a rebranding announced in June. His blank-check acquisition firm Falcon Peak Acquisition Corp withdrew an initial public offering registration on Friday after the charges were unsealed. Reporting by Jody Godoy in New York; editing by Jonathan Oatis and Rosalba O"Brien Our Standards: The Thomson Reuters Trust Principles.