Slaughter and May has won a choice instruction from 3i over its impending rights issue.

Martin Hattrell

Martin Hattrell

Corporate partner ­Martin Hattrell is understood to be representing the private equity group as it considers an equity raising of between £500m and £700m.

Hattrell has been advising the group on how to deal with its £2bn debt mountain for several months.

Slaughters has emerged as key adviser for 3i on its listed activity. The firm acted on two flotations of two funds in 2007, with ­corporate partner Kathy Hughes and Hattrell advising on the £700m IPO of an infrastructure fund in March, as well as the flotation of 3i Quoted Private Equity in July that year.

Other advisers on the investment side include ­Travers Smith, Macfarlanes and Clifford Chance.

3i traditionally picks advisers based on individuals rather than firm expertise. Chris Hales of Travers Smith is on the panel – he acted on 3i’s purchase of a majority stake in lingerie chain Agent Provocateur in November 2007.

Macfarlanes’ private equity partner Charles Meek is also on the 3i roster, ­having previously led on the acquisition of financial adviser Bestinvest in 2007.

Clifford Chance partner James Baird has a close ­relationship with the private equity group, with the firm also acting on fund formation matters.

3i’s general counsel is Kevin Dunn, a former managing director of General Electric who took over in November 2007 following the retirement of longstanding general counsel Tony Brierley. Dunn oversees a team of 14 solicitors at the group’s headquarters in Westminster.

After news of the rights issue plan was leaked to the Daily Telegraph, the group released a statement saying it was “considering a range of financing options including the potential issue of new equity”.

3i is expected to make an announcement after reporting its annual results later this month.