The Independent Police Complaints Commission is investigating 14 referrals relating to child sex offences from the 1970s to the 2000s.
It said the claims were of “high-level corruption of the most serious nature”.
The Met said it had voluntarily referred the allegations.
Sarah Green, deputy chairwoman of the IPCC, said: “These allegations are of historic, high-level corruption of the most serious nature.
“We will oversee the investigations and ensure that they meet the terms of reference that we will set.
“Allegations of this nature are of grave concern and I would like to reassure people of our absolute commitment to ensuring that the investigations are thorough and robust.”
The force said in a statement: “The allegations emerged whilst officers were working on Operation Fairbank and relate to the period between 1970 and 2005.
“The MPS [Metropolitan Police] recognised the severity of the allegations, and the importance of understanding whether or not our officers had in the past acted inappropriately, and therefore voluntarily referred the 16 separate allegations to the IPCC.
“Ongoing investigations and recent convictions by officers from the Sexual Offences, Exploitation and Child Abuse Command have shown that the MPS is fully committed to investigating non-recent allegations of sexual abuse.”
The original allegations of child abuse are also still being investigated by the Met.