Seven people have been arrested by fraud investigators as part of a criminal investigation into collapsed law firm Axiom Ince and around £66 million of missing client money.

The Serious Fraud Office (SFO) said over 80 of its investigators, accompanied by Metropolitan Police officers, conducted nine raids across the South East early on Tuesday morning to bring people in for questioning and search for possible evidence.

It comes after Axiom Ince was shut by the Solicitors Regulation Authority last month, when about £66 million of client money was found to be missing from its accounts and had been spent.

There are a number of significant questions that need to be answered. Clients from this law firm are missing many millions of pounds and more than 1,400 of its staff have lost their jobs. The impact on those affected is extremely serious

The law firm employed more than 1,400 staff across 14 branches in England and Wales before it was closed.

Investigators will also look at how funds passed from Axiom’s client accounts held with banking giant Barclays to the State of India to fund the purchases made with client cash.

Axiom Ince was founded in May this year when law firm Axiom DWFM bought corporate and commercial law firm Ince Group, as it was set to enter administration.

Just two months later, Axiom Ince then also snapped up struggling insurance law firm Plexus.

Nick Ephgrave, director of the SFO, said: “There are a number of significant questions that need to be answered. Clients from this law firm are missing many millions of pounds and more than 1,400 of its staff have lost their jobs. The impact on those affected is extremely serious.

“This morning, we have used our specialist powers to obtain important information that will help us get to the bottom of what happened.”

The Metropolitan Police referred the case to the SFO due to the complexity of the alleged fraud, but both will continue to work closely together on the investigation.

London-headquartered Axiom DWFM had 19 partners and fewer than 150 staff before the deals to buy larger London rival Ince Group, and than Leeds-based Plexus.