By Brendan Pierson

NEW YORK (Reuters) - Former Trump campaign chairman Paul Manafort must face mortgage fraud charges against him in New York, even though he is already serving a prison sentence after being convicted of similar federal crimes, New York state prosecutors said on Wednesday.

Manafort's lawyers had sought to dismiss the state charges in September, arguing that they subjected him to illegal double jeopardy, or prosecution of a person twice for the same offense.

“We continue to believe that the indictment should be dismissed in its entirety for the reasons stated in our motion," said Todd Blanche, a lawyer for Manafort.

"Notably, the District Attorney does not contest that the New York case arises out of the same transaction as the conduct for which Mr. Manafort was previously prosecuted by the Special Counsel. As we previously argued, we do not believe any exception under New York law applies and the indictment should be dismissed.”

However, the office of Manhattan District Attorney Cyrus Vance said in a court filing that double jeopardy did not apply because the jury in Manafort's federal trial was hung on some of the charges, and because New York's mortgage fraud laws were designed to protect homeowners, while federal law was aimed at protecting banks.

The state case, Vance's office said, is "exactly the type of prosecution that New York's double jeopardy statute explicitly permits: a successive prosecution where the harms caused to New York were not redressed by the prior prosecution."

A lawyer for Manafort could not immediately be reached for comment.

Justice Maxwell Wiley is expected to rule on Manafort's motion on Dec. 18, when Manafort is due to appear in Manhattan Supreme Court.

Manafort faces 16 criminal counts in New York. The charges include mortgage fraud, conspiracy and falsifying records related to his efforts to obtain millions of dollars in loans on properties in New York and elsewhere between 2015 and 2017.

The charges center on mortgage applications to three banks involving properties in Manhattan, Brooklyn, the Hamptons and California. The loans were also at issue in Manafort's trial in federal court in Virginia last year.

Manafort is currently serving a 7-1/2-year sentence following his conviction in the Virginia case and another federal case in Washington related to his lobbying work for pro-Russian politicians in Ukraine.

Under New York law, a person can be prosecuted twice for the same act only in specific circumstances, including when at least one element of the crimes is distinct and the statutes address "very different kinds of harm or evil."

The New York charges are widely viewed as an attempt to ensure that Manafort serves significant prison time even if Trump pardons him, which the president has not ruled out.

(Reporting By Brendan Pierson in New York; Editing by Bernadette Baum)