The New Jersey politician is accused
of using his influence to illegally benefit a Florida eye doctor, who he admits
is a long-time friend.
At a press conference, he said he was
"outraged" by the charges and dismissed the allegations as false.
The 14 charges include conspiracy and
making false statements, as well as eight counts of bribery.
Mr Menendez has resigned as the top
Democrat on the Foreign Relations Committee but vowed he "would not be
silenced" as he fights the allegations.
New
Jersey's largest newspaper, the Star and Ledger, has called on him to
resign his Senate seat.
In recent years, the senator has been
an outspoken critic of President Barack Obama's policies relating to Iran and
Cuba.
He is considered one of the most
influential Hispanic American lawmakers in Congress, and is the lead author of
legislation that would tighten sanctions imposed against Iran.
The
multi-year investigation first came to light in 2013, when federal authorities
raided the office of Dr Salomon Melgan - who was also indicted.
Their investigation focused on whether
Mr Menendez used his office to advocate in favour of Dr Melgan including by
intervening in a Medicare billing dispute.
Dr Melgan attracted more attention
last year when government data revealed that he had received more money from
Medicare reimbursements in 2012 than any other doctor in the United States.
He donated large sums of money to Mr
Menendez's re-election campaign.
"We celebrated holidays
together," he once told journalists. "We have been there for family
weddings and sad times like funerals and have given each other birthday,
holiday and wedding presents, just as friends do."
Mr
Menendez has admitted to taking multiple trips to the Dominican Republic on the
doctor's private jet and initially failed to properly pay for the trips. In
2013, he reimbursed Dr Melgan for two of the flights.
Later, his office admitted to another
flight on the jet - from Florida to New Jersey in 2011 - and said that the
senator had repaid Dr Melgan for it.
Mr Menendez, 61, has served in the
Senate since 2006, and was in the House of Representatives for more than a
decade before that.
The senator is expected to make a
statement later.
