Dibb Lupton Alsop claims to have launched the UK's first "rapid response team" to advise on emergencies - but rivals claim that they have provided the service for years and that it is a marketing gimmick by Dibbs.
A round-the-clock service manned by a 30-strong Dibbs team plans to cash in on providing immediate advice on crises such as environmental catastrophes and dawn raids by regulatory authorities.
Neil Gerrard, head of Dibbs' regulatory group, says: "Raids and prosecutions by regulators are on the increase, pushed on by pressure from government."
Norton Rose, Nabarro Nathanson, Herbert Smith and Taylor Joynson Garrett are among the firms which say this is part of normal service.
"That's what we've got," says a Norton Rose spokeswoman. "All our lawyers are contactable and our switchboard is manned 24 hours a day, 365 days a year."
She says that aside from the "disaster group", lawyers offer clients a hotline service for ongoing litigation.
James Bagge, who heads regulatory matters for the Norton Rose disaster group, says: "We are ready, willing and able to turn out if it is an emergency."
But he says: "I wouldn't have a whole team ready and waiting."
A spokesman at Nabarros dismissed the move as a "marketing ploy", saying: "It sounds like the repackaging of an old service with new clothes."
A spokeswoman for Dibbs says: "We never do any gimmicks."
Gerrard justifies the move, saying: "Companies and their directors need to appreciate the legal ramification of a regulator's interest from the earliest moments if they are to maximise their opportunities to limit damage."