Ashurst has hired Allen & Overy (A&O) energy partner Charles Williams forits New York office.

Williams, who has been a partner at A&O since he was made up in 2007, focuses on the US public-private partnership market – known as P3 in the US – which he has been involved in since its inception in the late 1990s. He joins Ashurst's energy, resources and infrastructure practice.

He advises the public sector, sponsors and lenders across projects in the transportation sector, as well as clients working on renewables projects in the US, Central and South America. He has also provided counsel to the US Department of Energy on several solar projects.

Jason Radford, the head of Ashurst's energy, resources and infrastructure team in the Americas said: "Combining Ashurst's credentials as a leading international firm in the P3 and renewables field with our US public finance capability provides us with a very strong platform for our US practice.

"The US has the potential to become one of the world's largest PPP and renewables markets and we are confident that the addition of Charles to our team will allow us to capitalise on the significant opportunities in these sectors."

Williams added: "To date the US P3 market has been dominated by transportation projects but increasingly we are seeing other sectors develop, including water/waste water and social infrastructure."

The appointment brings partner headcount in Ashurst's New York office to 11. The firm made a major push into the US in 2009 with the hire of a 10-partner, 30-lawyer US finance practice from US ally McKee Nelson.

In June, the firm won energy and infrastructure team of the year at Legal Week's Middle East Awards for its work advising Etihad Rail on the UAE's ambitious project to build a federal railway.