Sen. Bob Menendez, D-N.J., is defending himself against new allegations that he improperly assisted two fugitive bankers from Ecuador.

Federal criminal investigators looking into the senator's relationship with a Florida eye doctor also are reportedly asking questions about the senator's efforts on behalf of William and Roberto Isaias and whether the brothers' campaign donations influenced his work to help them remain in the United States, according to a NBC4 New York news report Thursday evening citing “multiple current and former U.S. officials.”

In a statement, Menendez spokeswoman Tricia Enright said the allegations are the latest in a “false smear campaign” and are reliant on “anonymous sources making outlandish” claims.

“Our office works each year with literally hundreds of individuals and families from across the country who are seeking help with the immigration process,” she said.

“We review each and every request we receive, and if we feel any inquiry is appropriate, we make it. In this particular case, Senator Menendez believed the Isaias family had been politically persecuted in Ecuador, including through the confiscation of media outlets they owned which were critical of the government.”

Enright said Menendez and his aides are not aware of any inquiry into the senator's actions in the matter and welcomes the review of the facts because the senator's actions “have been appropriate, and we believe the facts will confirm that.”

The two brothers have lived in the United States for more than a decade but were sentenced in Ecuador for embezzling millions as the bank they ran there was failing.

The Isaias now live in Coral Gables, Fla., but Ecuadorian officials have accused them of absconding with $100 million from Filanbanco, which collapsed back in the 1990s, along with several other of the country's banks.

A U.S. ambassador to Ecuador has recommended that the Isaias brothers be extradited to Ecuador to face trial, but the Justice Department says the Ecuadorean government has not provided enough evidence to warrant it.

The brothers maintain their innocence and have said, through their lawyer, that they didn't steal the money and are victims of political persecution. They have been seeking permanent residence in the United States and solicited Menendez' assistance.

The NBC4 news report says Menendez has written letters and made phone calls to the Department of Homeland Security and the State Department in support of the brothers.

The two brothers, which as non-residents in the United States cannot donate to political campaigns, say they have not made any donations to Menendez or any other politician. Federal election records show relatives of the Isaias brothers as giving $10,000 to the senator's 2012 campaign and at least $100,000 to the Democratic party in 2012.

The FBI also is investigating Menendez' ties to Florida eye doctor Salomon Melgen, a major campaign donor, twice searching the doctor's office in connection with an $8 million Medicare billing dispute. Melgen as denied any wrongdoing.

While one part of the probe is focused squarely on Melgen's alleged Medicare fraud, federal investigators are separately reviewing whether Menendez improperly acted to help Melgen with a deal to secure a port security contract in the Dominican Republic.

Last year, Menendez returned $58,000 to Melgen after news reports chronicled three trips Menendez took on Melgen's private jet — two of them to a resort in the Dominican Republic.