The director of the Serious Fraud Office (SFO) has said it is crucial for the office to retain its independence and spoken out against being merged into the National Crime Agency.

David Green was giving evidence at a justice committee hearing into the work of the SFO.

Asked whether he was concerned that the SFO could be incorporated into the NCA, Green said he was not ‘immediately concerned’ by the threat but that, like other institutions, he would make a case for its work, as any such move ‘could disrupt ongoing investigations and could undermine staff retentions’.

Green was responding to suggestions that the SFO could become ‘absorbed’ into the NCA following an announcement in February this year whereby the agency was handed more power over the SFO, telling it when it should take up bribery investigations.

Green said the agency has ‘long had powers to direct us to do specific things’ and that he assumed the new powers would ‘allow the NCA to ask me to consider whether to open an investigation. As it stands I have to decide that’.

He said retaining the so-called Roskill model, in which investigators and prosecutors work together from the start of a case, would also be crucial to its work.

‘The Roskill model, retaining independence and making sure fraud is seen as a priority, are all aspects of the SFO’s that should be retained,’ Green said.

He added that the office could lose its effectiveness if its remit becomes a lesser priority by being swallowed up into another department.

‘If you become part of an organisation that has eight or nine priorities, as the NCA does, then an organisation like ours, which has a very specialist focus, will have to compete. Inevitably, as it has done in the past, fraud could lose out.’

He added: ‘If you look at some of the companies we have worked with – Rolls Royce, Barclays, GSK – these are very powerful companies and I would suggest we need visible and demonstrable independence from central government.’