Other law firms have pushed trainee pay beyond the median. Freshfields Bruckhaus Deringer starts its trainees on 38,000 and US firm Paul Hastings Janofsky & Walker pays 40,000.
The nationwide median is 23,500, which includes professional services outside of the City.
The AGR study goes on to show that City firms are becoming more competitive, with more than two-thirds looking for a minimum qualification of a 2:1.
Carl Gilleard, chief executive of AGR, said that the study of 219 employers shows that there are many job opportunities out there for graduates.
However, he warned: Graduates must realise that academic achievements are not enough to secure a position and focusing on developing softer skills such as team-working is important for graduate-level positions.