Sources close to Khan warn it would be "unacceptable" if London doesn't receive the necessary funds, accusing Reeves of potentially pursuing an "anti-London agenda" similar to previous Conservative governments.
City Hall is concerned London may not receive any of the £113 billion unlocked for infrastructure spending, with key priorities including extending the Docklands Light Railway and the Bakerloo underground line.
Reeves has indicated a focus on prioritising spending outside of London and the South East, allocating over £15 billion to mayoral authorities in other regions.
The spending review is expected to allocate a significant boost to the NHS, with other departments, including the Home Office, facing budget squeezes.