A teacher from a Christian school has been charged with 84 separate counts of sexual abuse after it was claimed he abused students over a four year period.

Fifth grade teacher Curtis Van Dam, 35, of Sioux Center Christian School in northwest Iowa, US, is accused of abusing an unknown number of pupils from the school between August 2013 and October 2017.

Authorities say charges were filed after a complaint was lodged with police on 18 October, alleging inappropriate conduct between the teacher and a pupil at the school.

But since the original allegations were made 140 separate charges have been filed, including 14 counts of sexual exploitation by a teacher.

A statement published by the school reads: "We have been told from the beginning that additional charges for a former teacher at Sioux Center Christian would be coming.

"Today, Mr. Curt Van Dam, was charged with 101 felonies and 39 misdemeanours.

"On Oct 18, within hours of hearing a complaint, school officials removed Mr Van Dam from the school and immediately contacted authorities. His employment was terminated on Oct 19 and we have been in full cooperation with civil authorities since.

Sioux teacher allegations: "When you have involvement of a student, a teacher and a school setting, it's a tragic situation"

"We’ve wept, now it’s time to weep again. We’ve prayed, now we need to continue praying. We’ve brought our anger and fears to the Lord, and now we need to lay those feelings again at His feet," the statement read.

School Administrative Assistant Cheryl Haan told Newsweek that the exact number of students affected by the allegations is still unknown.

"This case is in the hands of our criminal justice system and we trust that justice will be served. Though the number of charges do not necessarily reflect the number of students, we are grieved again as we hear the extent of the charges.

The school that Mr Van Dam, 35, was a teacher at for 13 years. (Sioux Center Christian School)

The statement also offered reassurance to parents and children: “Kids, we want you to know that we consider you brave for telling your parents, the police, and the interviewers what happened to you.

A tweet sent from the school's official Twitter account appeared to offer a form where students and parents could sign up to therapy sessions with a school pastor, although the form is now "no longer accepting responses".

"We praise God that your testimony has brought to light a dark secret that none of us adults knew was there.

"Please know that thousands are lifting you before the throne of your Father in heaven.... Trust Him to restore you completely.

"Our focus at Sioux Center Christian continues to be the Christ-centered education of our students, while also providing daily support and guidance to students as needed through their teachers and professional counsellors.”

Mr Van Dam has been charged with 14 counts of Sexual Exploitation by a Teacher; 72 counts of Sexual Abuse in the 2nd Degreee; 12 counts of Sexual Abuse in the 3rd Degree; 2 counts of Lascivious Acts With a Child; 1 count of Lascivious Acts with a Child; 34 counts of Lascivious Conduct with a Minor and 1 count of Indecent Exposure.