A Florida woman pleaded guilty to forced labour charges after she admitted to smuggling a Mexican woman across the border, holding her captive while attempting to impregnate her with syringes.

Esthela Clark, 47, of Jacksonville, told a courtroom that she paid about $3,000 to have a woman smuggled across the border from Mexico to be a pregnancy surrogate.

According to WKMG Orlando, Clark had assured the victim – known in court as Y.L. - the surrogacy would be medically supervised. Instead, Y.L. was forced mentally and physically abused, forced into domestic labour and held captive while being fed a beans-only diet.

Clark attempted to impregnate the victim using syringes filled with sperm from Clark's boyfriend, which was collected from used condoms.

"Once those efforts did not work, Clark forced Y.L. to have sex with two complete strangers through threats of force and coercion,” court documents stated.

Y.L. was allowed to work, but Clark kept her earnings and threatened her family if she attempted to escape, the Daily Mail reported.

The abuse lasted more than two years before police stepped in. Cops were tipped off after an acquaintance of the victim intervened.

In 2015, Clark was hit with several charges including bringing in and harbouring aliens, sex trafficking of children, forced labor and furthering slave traffic.

The woman's lawyer asked for a competency hearing. Courts deemed Clark fit to stand trial.

Clark has yet to be sentenced, but could face up to 20 years in prison.