A new property survey shows that US law firms have set their sights on more than three acres of prime office space in the City of London since the beginning of the year, as part of a startling growth spurt.

The survey, by Chestertons property consultants, reveals US firms have taken over, or are actively searching for, a net additional 137,000sqft.

When compared with the 180,000sqft occupied by US firms at the start of the year, this is a jump in demand of more than 76 per cent.

Recent movers in the City include Jones Day Reavis & Pogue, which has taken over 15,000sqft; Brobeck Hale & Dorr (11,000sqft), Dewey Ballantine (11,000sqft) and Brown & Wood with approximately 12,500sqft.

The survey also shows that seven other firms, including Debevoise & Plimpton, Weil Gotshal & Manges, Arnold & Porter and Maples Calder, are in the market for as much as 101,000sqft of office space.

Skadden Arps’ recent acquisition of 25,000sqft of space at Canary Wharf in the East End does not appear among these figures.

Mark Bourne of Chestertons warns the figures show the increased threat US lawyers represent to UK firms.

“There has been a noticeable trend over the last few years for US firms to change their business strategy,” he said. “No longer are they content just to service US corporations in the UK, they are now recruiting British lawyers and seeking to compete aggressively with UK firms for a wide range of legal services.”

David Ayres, of Brobeck Hale & Dorr, said his firm needed to move because it had outgrown its present space. “We have expanded substantially in the last two years, and will continue to take on new attorneys, both US and English,” he said.