The investigation into Jeffrey Epstein, the Wall Street financier charged with underage sex offences, has expanded to a sprawling ranch he owns in New Mexico's high desert.

Epstein's "Zorro Ranch," worth $12 million, is in the hills outside Santa Fe and has a private runway for his plane, stables, and perfectly manicured gardens.

The office of New Mexico attorney general Hector Balderas confirmed it was investigating allegations against Epstein, and interviewing people who allege that they were victims.

Mr Balderas has been in contact with prosecutors in New York, where Epstein has already been charged and is awaiting trial.

Epstein, 66, was first convicted of underage sex offences in 2008 when he agreed a plea deal in Florida. He admitted a single charge of soliciting a minor for prostitution in exchange for a 13 month jail sentence, and registering as a sex offender.

Shortly after completing his sentence he bought the New Mexico ranch from the family of the late New Mexico governor Bruce King.

Under New Mexico law he was not required to register as a sex offender there. According to local reports Epstein did voluntarily contact the sheriff's office in Santa Fe when he bought the ranch, alerting them about his conviction. But the New Mexico Department of Public Safety then told him he did not need to.