Clifford Chance (CC) is suing the City of New York after the firm's local office lost connection to its business network for more than 60 hours last August.

In a lawsuit against the city, the firm is asking for $127,500 (£100,000) in alleged damages to make up for its lost productivity during the network outage. CC claims that the cause of the outage was construction work at a pedestrian crossing.

"We are tremendously disappointed to have had our work disrupted and livelihood threatened by the [Department of Transportation] without warning, apology, much less compensation," complained James Paul, a New York partner and general counsel at the magic circle firm.

City officials are expected to respond to the lawsuit in Manhattan Supreme Court next month, according to court papers.

In a letter filed with the court, Paul said the firm's network connection to its data centre was interrupted last August due to transportation department work on 53rd Street.

Writing to New York City comptroller Scott Stringer, Paul said the transportation department accidently cut the internet conduit while digging at a crosswalk, resulting in a network disruption of 63 hours that caused "tremendous inconvenience and lost productivity".

"While we understand some disruption in service is unavoidable when maintaining New York City's infrastructure, we are deeply concerned with the apparent lack of accountability at the Department of Transportation for the interruption," Paul said, noting that, had it not been for the firm's existing business interruption coverage, "which we incurred at significant expense", working during the outage would have been impossible.

"Our productivity was significantly curtailed," while the firm's non-lawyer staff had to work many hours over a weekend and in the evenings to ensure the firm could open for business on the following Monday, Paul wrote.

Paul added that the firm was not contacted by the transportation department or anyone from the city about the disruption and it only confirmed through its landlord that the department's work was the cause.

CC has long maintained a New York City office and its lawyers and staff "reside (and pay taxes) here", Paul said.

Paul noted the firm's New York office has 193 lawyers and 170 staff, who are part of the global firm's overall headcount of 3,300 lawyers and 2,767 staff.

A spokesman for Stringer's office could not immediately comment. Paul declined to comment on the firm's lost productivity or the suit.