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The former member of Congress and New York City mayoral candidate sent the teenager graphic sexual messages, asking her to do things like dress up as a "school girl," according to screen grabs of conversations published by the Daily Mail.
Weiner and the unidentified 15-year-old frequently talked on Skype as well, according to the report.
He also sent her several shirtless photographs of himself.
The charges were not denied by Weiner, who released a vague statement to the Daily Mail indicating he had been the victim of a "hoax" but saying he had "repeatedly demonstrated terrible judgment about the people I have communicated with online and the things I have sent."
Last month it was announced that Weiner had split up with his wife, top Hillary Clinton aide Huma Abedin, after the New York Post reported he had been sexting with another woman.