Norton Rose's Singapore alliance partner Lee & Lee has severed its ties with the UK firm after 19 years.
Norton Rose claims that the decision was taken after talks about the firms' futures following planned changes to Singapore law that will allow English lawyers to practise domestic law.
A spokesman says this will allow Norton Rose to move into the province of practising Singaporean law, a role traditionally reserved for Lee & Lee within the alliance.
But he admits that the Legal Profession (Amendment) Bill may not come into effect for a number of years and refuses to explain why, if this is the reason for the separation, the firms did not wait until the proposal became law.
"I can't say why we did this before the law came into effect," he says.
But he adds: "At the instance of Lee & Lee the association has been terminated."
Norton Rose has nine partners and 25 assistants in its Singapore office, which practises only UK law.
Lee & Lee was severely weakened last month by the defection of its entire litigation team - seven partners and up to 10 associates (The Lawyer, 28 February) - who left to set up a rival firm.
Roger Birkby, Norton Rose's managing partner, confusingly says: "Lee & Lee is an excellent firm. We will be happy to continue to instruct it on corporate and litigation matters."
Norton Rose senior partner David Lewis said at the time that he was not bothered by the split at Lee & Lee and that he may form a new alliance with the dissident partners.
Lee & Lee's former head of litigation, Tan Kok Quan, one of the leaving partners, is to set up the new operation in April with several of his former partners, along with corporate and property boutique law firm Khoo Aeria & Partners.
Quan refuses to say why he is leaving Lee & Lee.
His new firm will be called Tan Kok Quan & Partners and is expected to offer a full range of services.
Quan says he is looking for a formal UK or US tie-up.