June 4 (Reuters) - The Federal Communications Commission said on Tuesday it was investigating why consumers in multiple U.S. states are unable to make wireless calls.

AT&T said in a statement "there is a nationwide issue that is affecting the ability of customers to complete calls between carriers. The carriers are working as quickly as possible to diagnose and resolve the issue."

The FCC and New York Attorney General Letitia James said in February they were investigating the cause of an AT&T outage earlier that month as well as the telecom firm's response. The outage lasted for up to 12 hours. (Reporting by David Shepardson in Washington Editing by Leslie Adler and Matthew Lewis)