(Reuters) - IBM Corp (IBM.N) and T-Systems, Deutsche Telekom's (DTEGn.DE) struggling IT services and consulting business, plan to sign an agreement to jointly provide mainframe services, an IBM spokesman said on Monday.

Existing customer contracts will not be affected by the arrangement, which is subject to standard approvals, the spokesman said in an emailed statement to Reuters.

"T-Systems will continue to offer mainframe services, but will subsequently provide these services with IBM," he said.

A T-Systems spokesman had declined to comment on the financial aspect of the arrangement on Sunday but confirmed that the company was deepening its cooperation with IBM in mainframe services and would operate together from May.

(Reporting by Sathvik N in Bengaluru and Jim Finkle in New York; Editing by Gopakumar Warrier)