Katie Holmes filed for divorce in order to save her daughter from undergoing Scientology auditing.

The 33-year-old actress ended her marriage to Tom Cruise - who is a high-profile member of the quasi-religious cult - last week and sources close to the star have revealed she was worried their six-year-old daughter would be subjected to a process known as ''sec checking'', according to TMZ.com.

During these tests the subject holds electrode handles on a device called an electropsychometer or E-Meter and is then asked a series of personal questions that help the church locate ''areas of spiritual distress'' but according to ex-members it is designed to help kids spy on their parents.

While the person is being asked the questions, a church auditor collects E-meter readings from the device, which has been compared to a polygraph machine.

According to former Scientology member and Oscar-winning director Paul Haggis, the tests often help members to remember past lives.

He previously explained: ''If you're having a fight with your girlfriend, the auditor will ask, 'Can you remember an earlier time when something like this happened?' And if you do, then he'll ask, 'What about a time before that? And a time before that?' ''

It has also been claimed Katie ended the marriage because she was concerned Tom wanted to send Suri to the Sea Organisation - a floating Scientology school.

Those on board the ship are required to commit themselves to the quasi-religious sect for a billion years and allegedly asked to disconnect from any non-believers.