The Healthcare Commission confirmed that it would examine concerns about services at Birmingham Children's Hospital at the request of the Secretary of State for Health.
Nigel Ellis, the Commission's Head of Investigations, said: "We cannot comment in detail at this stage, however we are taking the concerns raised very seriously. We will publish an independent report detailing our findings, in due course."
The Commission is liaising with Monitor and has already been in contact with the Birmingham Children's Hospital Foundation NHS Trust.
Healthcare Commission