A new report states that London attracts a quarter of all graduates from UK's top universities, causing a "brain drain" that leaves other UK cities needing more skilled and talented workers.

The report, "The Great British Brain Drain: Where graduates move and why," was published by think tank Centre for Cities on Monday. The think tank found that 24.4 percent, almost a quarter, of all graduates in the UK in 2014 and 2015 have relocated to London and found jobs within six months after finishing their degree.

The Centre for Cities also found that London was pulling all top-performing graduates from top universities. The capital attracted more than a third (38 percent) of graduates with first-class or upper second-class degrees, all of them coming from "Russell Group universities," which is made up of UK's top 24 universities.

For graduates of Oxford and Cambridge Universities, collectively known as "Oxbridge," the trend was even more evident: More than half (52 percent) of Oxbridge graduates moved to London for work after university.

London also retained much of its graduates, and had the highest graduate retention rate compared to other cities in the UK. London saw 77 percent of its students staying to work after graduation, and saw 74 percent of its locals return after graduating from university in a different city.

The Centre for Cities found that job offerings were the most important factors influencing the brain drain, along with possible career progression. It also found that wages, or the amount of compensation offered for respective job offerings, isn't as influential as compared to the other factors mentioned.

"Wage subsidies and other specific graduate retention policies will not tackle the root causes of this issue. Instead, the priority for national and local leaders should be strengthening city region economies, and increasing local demand and opportunities for graduates," Alexandra Jones, Centre for Cities' chief executive, told The Guardian.

"The government will not achieve its vision of extending prosperity and growth across the country unless it takes steps to help more cities attract and retain the UK's top talent."