"I have decided to change my party affiliation. The decision has been preceded by a longer period of stress and pressure from the group leadership," Nyberg writes in an email to TT.
Now she has formally requested to resign from the Riksdag group and thus becomes a member without a party affiliation, commonly known as an independent.
Katja Nyberg left the SD after she was suspected of driving under the influence of alcohol and drugs - accusations she denies.
In her email to TT, Nyberg also writes about the "intensive media coverage" she has experienced.
"My hope is that this decision will help stabilize the situation," she writes.
