SJ Berwin is set to lose a team of funds lawyers in addition to the two partners exiting to join Proskauer Rose.

The resignation of the team of associates, who are moving to the US firm alongside departing partners Nigel van Zyl and Oliver Rochman, will be seen as a further blow to the top 20 UK firm, which is especially well-known for its heavyweight funds practice.

Around six associates have resigned, although SJ Berwin said talks were still ongoing with the group about their departures.

A spokesperson for SJ Berwin said: "A number of funds associates have expressed their intention to leave to join Proskauer. It's always disappointing when staff decide to leave but this is an inherent part of law firms."

"We remain the market-leading player with one of the largest and strongest funds team in Europe. Over the past three years, SJ Berwin has closed more European and international private equity funds than any other firm."

Van Zyl has been a key player in SJ Berwin's funds group, where he made partner in 2007. During his time at the firm he has worked with clients including HgCapital, Lion Capital, Hermes Private Equity, Unilever and Rabobank.

Following the departures the SJ Berwin corporate funds team has a total of nine remaining partners and 18 associates, although the firm said it also has lawyers working on funds across other areas such as tax, regulatory, funds finance and litigation, bringing the combined size of the London team to 22 partners and 33 associates.

SJ Berwin and Proskauer Rose held protracted merger discussion for most of 2010, with the discussions understood to have eventually broken down due to the disparity in the firms' profitability, as well as cultural differences.

Proskauer has since made a number of notable London lateral hires, including private funds partner Kate Simpson from Kirkland & Ellis, who trained at SJ Berwin, as well as Berwin Leighton Paisner funds partner Peter McGowan.

The firm also added Jones Day London head Russell Carmedy and the US rival's European private equity head Michael Nouril earlier this year.