Boris Johnson has branded the EU's proposed bonus cap a "deluded" and "self-defeating" policy.
The Mayor claims that limiting bonuses to a maximum of twice a banker's salary will only serve to boost financial centres outside the EU.
He said: "People will wonder why we stay in the EU if it persists in such transparently self-defeating policies. Brussels cannot control the global market for banking talent. Brussels cannot set pay for bankers around the world.
"The most this measure can hope to achieve is a boost for Zurich and Singapore and New York at the expense of a struggling EU. This is possibly the most deluded measure to come from Europe since Diocletian tried to fix the price of groceries across the Roman empire."