Over a period of three decades, police working undercover to infiltrate protest groups adopted the identities of dead children without notifying their parents, The Guardian reported Monday.
Pat Gallan, a deputy assistant commissioner for the Metropolitan Police, will address the revelations at a hearing of the home affairs select committee Tuesday.
Keith Vaz, chair of the committee, has called the practice "gruesome."
Gallan is head of the police department's professional standards division.
Scotland Yard has already launched an investigation into the practice, which was used by a secretive police unit disbanded in 2008. Dozens of officers in the unit are said to have gone through birth and death certificates to find a dead child who matched their alias.
The officers created driver's licenses, national insurance numbers and other documents in the name of the dead child and visited the neighborhoods of the child's family.