Clifford Chance (CC) has pledged to provide pro bono support worth £1m to legal aid practice Law For All (LFA) over the next five years.

The magic circle firm has signed a five-year agreement with longstanding pro bono partner LFA, which sees CC commit to supply up to five full time-equivalent trainees each year to the organisation – an investment CC estimates at worth more than £1m over the period.

The move, which comes as legal aid budgets face spending cuts, comes after CC broke with convention and placed a value on its pro bono efforts in the 2009-10 financial year.

LFA advises clients who fall just outside the means test for legal aid or whose problems fall outside the scope of legal aid.

The organisation said CC's involvement in 2010 will help it see an additional 2,900 drop-in clients and undertake an extra 25% of casework for ongoing clients – with CC trainees representing around 190 clients in tribunals who would otherwise be unrepresented.

CC pro partner Roger Leese said: "In light of the unprecedented challenges that LFA – along with the rest of the legal aid sector – faces as a result of the public spending cuts, we wanted to demonstrate to them our long-term commitment to providing substantial and consistent pro bono support for their invaluable work."

Anna Barlow, chair of LFA's trustees, said: "We are delighted and honoured that CC has decided to formalise its pro bono involvement in a five-year service level agreement.

"Social welfare lawyers are under threat but our vital work for vulnerable clients will continue with the help of this generous commitment. The security of long-term involvement enables us to confidently invest in the future of our organisation."

Last month CC said it had committed a total of £17m to pro bono work in 2009-10, with the value estimation based on 57,071 hours invested by its lawyers in community and pro bono efforts.