Jan 22 (Reuters) - United Airlines said it had grounded all domestic flights due to an "IT issue" on Sunday, company spokeswoman Maddie King said.

"We are working as quickly as possible to resolve this issue and get out customers to their final destinations," King said in an emailed statement.

(Reporting by Ismail Shakil in Bengaluru and Suzanne Barlyn in New York; Editing by Lisa Von Ahn)