A COUPLE has been arrested after it was alleged they had 21 surrogate children living in their mansion alongside abusive nannies.

Guojun Xuan, 65, and Silvia Zhang, 38, are accused of endangering the young children they secretly kept inside their $4.1million Californian mansion.

The oldest kid was 13 with 17 others being under three years old.

Silvia is said to have wanted a big family so used her own surrogacy business to live out her dream home life, police believe.

Cops launched a grim investigation after receiving complaints of a two-month-old who had suffered a traumatic brain injury.

It is believed the baby was injured by one of the nannies hired by the couple.

Chunmei Li, 56, is charged with employing verbally and physically abusive discipline methods, as captured by security cameras showing some of the alleged incidents.

Arcadia police Lt. Kollin Cieadlo stated: “The discipline, both verbal and physical, was so severe that it substantiated the belief that child abuse was taking place inside the home.”

Officers then searched the mansion and found the couple with 15 children inside their Arcadia home, according to KABC.

All of the children have now been taken into custody by social services.

It is believed that all the children are the offspring of Xuan and Zhang but were birthed through dozens of mothers across the US.

The unsuspecting parents had all been hired through the couple’s surrogacy business, according to police.

Lt Cieadlo says that the pair would took legal guardianship of the kids once they were born.

The couple have since been arrested over child endangerment.

They deny the claims and say officials are “misguided and wrong” as they simply wanted a large family.

The Arcadia police say the FBI has asked to be involved in their investigation as they look into a suspected mass-surrogacy operation.

A warrant is out for Ms Li’s arrest but she is yet to be tracked down.

After the couple’s arrest, shocked neighbors revealed that the sprawling nine-bedroom mansion, situated near Los Angeles, is designed like a hotel on the inside.

Local Art Romero even claimed to CBS News that there appears to be a reception desk in the entrance.

The shocking revelation has sparked fears across the US for those mothers who gave up their babies to Xuan and Zhang.

Surrogate mom Kayla Elliot, 27, told KABC: “It’s horrific, it’s disturbing, it’s damaging emotionally.

“These agencies, we’re supposed to trust them and follow their guidance and come to find out this whole thing was a scam, and the parents own the agency.”

Kayla says she is now fighting to get her child back and has set up a GoFundMe to help with the custody battle.

She said that her child “deserves stability, love, and a safe home”.

Xuan and Zhang have been released since due to the practice of having so many kids through a surrogacy not being illegal.

And experts fear that there may be a more worrying trend which deserves to be checked.

Executive director of the Center of Bioethics and Culture nonprofit, Kallie Fell, told KABC that hoarding the children will definitely be seen as suspicious.

She said: “What are the intentions of having that many children at home through these assisted reproductive technologies?”

Adding that it “smells of trafficking, child trafficking”.