NEW YORK (Reuters) - A fund-raiser who has contributed to New York City Comptroller John Liu was charged with wire fraud and conspiracy on Wednesday for evading campaign donation rules, dealing a blow to the comptroller's mayoral hopes.

The charges against the fund raiser, Xing Wu Pan, did not mention Liu, but said Pan illegally raised $16,000 for a candidate in a 2013 citywide race, according to a statement from the U.S. Attorney for the Southern District of New York and the New York Office of the Federal Bureau of Investigation.

Liu is expected to stand for mayor in the 2013 elections.

A spokesman for the U.S. Attorney for the Southern District of New York, Preet Bharara, declined to identify the candidate who received the illegal contribution.

"Pan is accused of engaging in a fraudulent scheme that involved the use of 'straw donors' to funnel a large, illegal campaign contribution to the campaign of a candidate ... for citywide elective office in 2013," Bharara and the assistant director-in-charge of the Office of the Federal Bureau of Investigation, Janice Fedarcyk, said in a statement.

The fund-raiser, also known as Oliver Pan, was a campaign donor for the comptroller in 2006, according to the New York State Board of Elections Financial Disclosure Report.

Pan could not be immediately reached.

In a statement, Liu said he was saddened, adding: "If it is true, then the conduct was clearly wrong and my campaign was not told the truth."

Liu, who served in the City Council before he was elected comptroller, is one of the most prominent contenders to succeed Mayor Michael Bloomberg, whose third and final term ends in 2013. The list of Democratic rivals also includes Liu's predecessor, William Thompson, City Council Speaker Christine Quinn and Public Advocate Bill de Blasio.

Pan's $16,000 contribution exceeded the amount individuals are allowed to contribute, which is one basis for the fraud charge, the federal officials said. The scheme also illegally boosted the amount of matching funds for which Liu qualified, they said.

(Reporting by Joan Gralla; Editing by Andrew Hay and Dan Grebler)