Global bank UBS put pressure on Stephenson Harwood not to represent junior trader Arif Hussein in relation to a Financial Conduct Authority (FCA) investigation, The Lawyer has learned.

In a phone call from a senior UBS lawyer to a Stephenson Harwood partner, the bank asked the firm to cease representing Hussein.

It is understood UBS attempted to leverage its relationship with Stephenson Harwood to get it to sack Hussein as a client. Hussein has been embroiled in a Libor-manipulation scandal and has been represented by regulatory and criminal litigation partner Sara George.

The bank is a longstanding client of Stephenson Harwood and often refers senior management individuals to the firm for representation.

Stephenson Harwood successfully represented UBS wealth management chief executive John Pottage in a 2012 legal battle with the Financial Services Authority (FSA). Pottage was cleared of misconduct following an appeal to the FSA Upper Tribunal and his £100,000 fine was overturned.

The firm was instructed by former UBS junior trader Hussein in 2013 in relation to a FCA investigation into Libor manipulation. The probe concluded in April 2016, leading to a decision notice blacklisting Hussein from financial services work for being “reckless”.

Hussein said he would challenge the decision before a tribunal. He has accused the FCA of doing a “cosy deal” with UBS during the investigation into him, which he believes relied on “incomplete, partial and misleading information”.

In a recent statement in response to the FCA’s decision notice, Hussein said: “UBS spent many millions of pounds on lawyers for itself and to protect its senior managers.

“UBS refused to contribute a penny to my legal costs and tried to pressurise lawyers not to represent me.”

A source close to Stephenson Harwood verified his claim, adding the firm “would never refuse to act for a client or not act for them properly on the basis of commercial pressure”.

The lawyer added that there was “no doubt” the issue has proved an “uncomfortable situation” for Stephenson Harwood.

Hussein has accused UBS of racking up millions of pounds in legal bills to protect current management during the investigation and said FCA investigators “abdicated all responsibility for evidence-gathering to lawyers defending the interests of UBS”.

UBS is represented by Gibson Dunn & Crutcher London partner Philip Rocher in the matter. The firm replaced Allen & Overy, which is understood to have withdrawn as UBS’s lawyers last year.

UBS has already paid out $1.5bn in penalties to settle Libor-manipulation allegations with authorities around the world. Tom Hayes, a former trader at UBS and Citigroup, was the first person to be convicted for conspiring to rig Libor. Hayes has instructed human rights firm Kaim Todner to appeal his conviction.

Stephenson Harwood and UBS declined to comment.