SAN FRANCISCO • Kip Moore, a country music singer-songwriter with hits such as Beer Money and Hey Pretty Girl, has had some disturbing experiences with fans lately.

At some shows, women have approached him demanding to know why he stopped chatting with them on Instagram or Facebook.

Some said they left their husbands to be with him after he said he loved them. Now they could be together, the women told him.

"They're handing me a letter, you know, 'Here's the divorce papers. I've left so and so,'" Moore, 38, said. "If I check my inbox right now, I'd have hundreds of these messages. But I try not to check it because it disheartens me."

Moore, fuelled by his country music fame, is a victim of what has become a widespread phenomenon - identity theft on social media.

Recent searches found at least 28 accounts impersonating him on Facebook and at least 61 on Instagram. Many of the accounts send messages to his fans promising love and asking for money. Those who get duped often direct their anger at the real Moore.

The issue of fake social media accounts masquerading as public figures is acute. Facebook, Instagram and Twitter teem with accounts that mimic ordinary people to spread propaganda or to be sold as followers to those who want to appear more influential.

But millions of the phoney profiles pose as actors, singers, politicians and other well-known figures to broadcast falsehoods, cheat people out of money - or worse.

Last year, the Australian authorities charged a 42-year-old man with more than 900 child sex offences for impersonating Justin Bieber on Facebook and other sites to solicit nude photos from minors.

The sheer volume of social media impostors poses a challenge to even the wealthiest celebrities.

In a video last year, Oprah Winfrey warned her Twitter followers that "somebody out there is trying to scam you using my name and my avatar on social media, asking for money".

Even Facebook's top executives, including Mark Zuckerberg, have struggled with impersonators.

To get a sense of the scale of the problem, The New York Times commissioned an analysis to tally the number of impersonators across social media for the 10 most followed people on Instagram, including Beyonce and Taylor Swift.

The study, conducted by Social Impostor, a firm that protects celebrities' names online, found nearly 9,000 accounts across Facebook, Instagram and Twitter pretending to be those 10 people.

Brazilian soccer player Neymar was the subject of the most fake accounts - 1,676. Pop star Selena Gomez was second, with 1,389, according to the analysis, which was completed in April and did not count explicit parody or fan pages. Beyonce had 714 impersonators; Swift had 233, the least among the group.

Twitter, Instagram and Facebook have compounded the problem with lax enforcement of their own policies prohibiting impersonators. Some people who report such accounts said the sites had gotten better at removing them, but others said the companies did not police them adequately.

Most people agreed that once the sites erased the accounts, they did little to keep those behind them from creating new ones.

"It's just a Band-Aid," Moore said.

Facebook and its Instagram unit said they were cracking down on fake accounts. The social network said it had recently added software that automatically detected impostors, which it used to remove more than 1 million accounts since March.

Yet in April, tucked away in the fine print of an earnings document, Facebook increased its estimate of fake accounts on the site by 20 million to as many as 80 million accounts or 4 per cent of the total number of accounts. It said the site's sheer size made it difficult to measure the problem.

The social media companies' main defence against fake accounts is users, whom they ask to report suspicious activity. Facebook recently added an option to report profiles as impostors.

Mr Scott Dickens, a Facebook product manager who develops tools to fight hoaxes, said the company was trying to stamp out every pretender, but that the task was complicated by the social network's size; the nuance of separating imitators from fan pages; and the sophistication of some of the impostors.

"It's the arms race," he said.

NYTIMES