Proskauer Rose's London head Matthew Hudson has left the US firm, it has emerged.

Hudson left Proskauer towards the end of January, having run the London office since its launch in 2007.

It is unclear what Hudson's next move will be, although he is believed to be discussing a new project with clients.

Hudson's departure leaves Proskauer with five partners in London. This includes US-qualified investment funds partner Mary Kuusisto, who is now serving as the acting office head.

Kuusisto transferred to London from Boston at the end of 2008 and has a particular focus on tax-related matters.

Private equity partner Hudson moved to Proskauer in 2007 from O'Melveny & Myers to launch the City office.

He had previously helped launch O'Melveny's City base when he joined the firm with former SJ Berwin colleague John Daghlian.

Prior to joining O'Melveny, Hudson held a number of in-house positions within the private equity industry, including stints with Cabot Square Capital and Collyer Capital.

A statement from Proskauer said: "We thank Matthew for his leadership in opening our London office and establishing a solid and growing presence in the market. We wish him well in his future endeavours."

Proskauer has taken a cautious approach to building in the City since its launch, saying that it intends to focus on three core areas: private investment funds, cross-border M&A and some specialised finance work.

Hudson could not be reached for comment.