A Maths teacher has confessed to having a year-long affair with a teenage student after her own daughter reported her to police.

Alberta Padilla, 52, started a sexual relationship with the 17-year-old boy while she gave him personal tuition at the Lady Bird Johnson High School in San Antonio, Texas.

Ms Padilla purportedly had sex with the teen in a public park & bought him gifts including food, clothes & a mobile phone after they started meeting to have sex.

She was arrested & charged with forming an indecent relationship between an educator & student after her daughter raised suspicions about the affair with the police, according to local news station KSAT.

Ms Padilla will face up to 20 years in prison if she is convicted.

According to an arrest warrant affidavit, one of her daughters had recorded the assumed victim asking her not to tell the police about the affair.

He purportedly said he had developed feelings for Ms Padilla.

Ms Padilla was arrested on Thursday on suspicion of forming an inappropriate relationship between an educator & student & is being held in Bexar County Jail after bail was set at $20,000.

A spokesperson for Ms Padilla’s employers, the North East Independent Schools District, said the defendant has been placed on leave.