A State Department employee at the US Embassy in London has been charged with a "sextortion" plot, in which he is alleged to have hacked sexually explicit photographs of young women in order to blackmail them.

Michael C Ford was arrested by federal agents in Atlanta, Georgia, earlier this week while about to embark on a flight back to the UK with his wife and 15-month-old son, after visiting his parents, reports Politico.

He is charged with stealing photographs from women as young as 18 from their internet accounts using his State Department computer.

At a Thursday hearing the prosecutor said Ford wanted to humiliate, torment and intimidate the women, by threatening to post their pictures online unless they complied with his demands and provided him with more explicit photographs and videos.

Magistrate E Clayton Scofield set a $50,000 bond and ordered him to be put under house arrest, banning any part of his home from internet or computer access.

"He targeted women at US colleges and universities and was looking for women who were members of sororities and aspiring models," prosecutor Mona Sedky of the Justice Department's Criminal Division's Computer Crime and Intellectual Property Section said, reports the Atlanta Journal-Constitution.

She accused Ford of emailing sexually explicit photos he stole of at least one woman to the woman's parents and brother.

An investigation was launched after an 18-year-old woman in Kentucky and a 22-year-old woman in Ilinois approached the FBI with claims their internet accounts had been attacked they were being subjected to attempted sextortion.

Ford allegedly used 'phishing' scams to access his victims internet account passwords, in which he would send fake emails from Google asking victims to verify their account details.

Investigators searched Ford's computer at the London Embassy and found a list of 262 email addresses.

"I believe that the account holders listed on the spreadsheet are all victims of Ford's criminal activity," Kasik wrote in the May 15 affidavit for the warrant.

He "apparently hacked into and stole compromising photographs from the online accounts belonging Jane Doe One," Kasik wrote in the affidavit. "He then demanded that Jane Doe One take videos of other girls" and "sexy girls" who were undressing in changing rooms at pools, gyms, and clothing stores, and then give the videos to him."

Ford, who has lived in the UK since 2005, faces charges of cyber-stalking and making interstate threats.