Allen & Overy (A&O) has seen the departure of US financial services regulatory head Douglas Landy to Milbank Tweed Hadley & McCloy.

Landy, who has been at the magic circle firm since 2008 after joining from Cadwalader Wickersham & Taft, joined Milbank yesterday (14 March).

He joins the US firm as a partner in its leveraged finance and financial regulations groups.

While at A&O Landy represented some of the largest US and foreign financial institutions, including JP Morgan, Citigroup, Deutsche Bank, the Royal Bank of Scotland, Bank of America, Credit Suisse, Morgan Stanley and Goldman Sachs.

He also provided regulatory advice to the Abu Dhabi royal family in 2008, when A&O was instructed to act on a £7bn cash injection into Barclays from the Middle East, which saw Qatar and Abu Dhabi secure a 30% stake in the British bank.

An A&O spokesman said: "We would like to thank Douglas for the contribution he has made during his time at the firm and wish him all the best for the future."

It is understood that A&O does not have imminent plans to replace Landy in the role. However, the firm is looking at expanding its regulatory offering in the US, which received a boost in 2011 with a launch in Washington DC via a team hire from O'Melveny & Myers.

The US has long been a difficult market for UK firms to attract and hold on to leading lawyers in the market, partly due a disparity in partner profits.