The U.S. Equal Employment Opportunity Commission is suing the Hawaii Medical Service Association for discriminating against a group of disabled workers.

The EEOC alleges the state’s largest health insurer denied occasional leave to employees with disabilities for medical treatment without offering other reasonable accommodations, violating the federal Americans With Disabilities Act.

In late 2013 HMSA “abruptly changed its policy on the use of intermittent leave as an accommodation for employees with disabilities,” forcing them to work without an accommodation or to resign, the U.S. Equal Employment Opportunity Commission charged in the complaint filed Thursday.

“HMSA complies fully with the Americans With Disabilities Act and its requirement for reasonable accommodation for employees covered by the ADA,” said HMSA spokeswoman Elisa Yadao, adding that the company wasn’t officially served with the lawsuit and couldn’t further comment.

The suit was filed on behalf of Marline Reyes, who worked as a customer relations representative in HMSA’s Hilo call center starting in April 2013. HMSA granted Reyes, who has type 2 diabetes and stage 4 renal failure, one to four days off per month for medical appointments starting in August 2013, but HMSA ended the policy as of January 2014. Reyes resigned that month.

“The termination of intermittent leave caused immense stress and anxiety” for Reyes, who “felt she could no longer attend all the required medical appointments without repercussions,” the lawsuit said.

Customer relations representative Sharolyn Burrell, who worked at HMSA’s call center for about 18 years from October 1996, was also named in the complaint. Burrell was diagnosed with degenerative disc disorder and spinal stenosis after developing back problems in 2010. The conditions “substantially limited her ability to stand, sit and walk for prolonged periods,” the suit said.

HMSA granted her one to three days off per month in 2012 and four to eight days off when her conditions worsened. But in October 2014 she was notified that she would no longer be able to take time off after exhausting her benefits under the Family and Medical Leave Act, which allows workers up to 12 weeks of unpaid leave per year while protecting their jobs. Burrell subsequently resigned, according to the EEOC.

The federal agency filed the complaint in U.S. District Court after failing to reach a settlement with the insurer. The EEOC is seeking back pay and other damages.

“Blanket employment policies that negatively affect a group of individuals can be discriminatory,” said Glory Gervacio Saure, director for the EEOC’s Honolulu office, in a news release.