David Green, who was appointed to his position in April 2012, would have seen his fixed-term role end this April had it not been extended until 2018.
"I am happy to continue as director, and the SFO will continue to take on the sort of cases for which it was designed," Green remarked.
Jeremy Wright, attorney general, added:
"In his time as director of the SFO David Green led a change in the organisation’s approach to prosecuting cases and delivered the first UK Deferred Prosecution Agreement and the first convictions under the Bribery Act 2010."
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Christopher David, counsel in WilmerHale’s UK Investigations & Criminal Litigation practice, pointed out that, despite Green's achievements during his time in the role, including the conviction of former trader Tom Hayes for offences related to manipulating Libor, the Office still had many cases underway.
"David Green will view his directorship as a job half done," David said.
The news of Green's reappointment comes less than a fortnight after six ex-brokers were acquitted of accusations that they conspired with Hayes to rig Libor.
At the time, Green defended the decision to take the case to court, remarking: "Nobody could sensibly suggest that these charges should not have been brought and considered by a jury."
High-profile cases still in progress for the SFO include its investigation into an accounting black role at supermarket Tesco, and Green will likely be judged on the result of this.
Jonathan Pickworth, partner and white collar crime expert at White & Case, suggested Green might take the opportunity to reflect on how he had approached his role to date, particularly given how much more aggressive his approach has seemed in comparison to his predecessor Richard Alderman.
"We need to see more carrot and less stick, including a return to civil settlements where relevant," commented Pickworth. "This approach would take a huge burden off the agency and save taxpayers’ money, enabling the SFO to focus its limited resources on the most complex cases of fraud and those which are in the public interest to secure a prosecution."
Meanwhile, Stephen Parkinson, head of criminal litigation at Kingsley Napley, called today's decision "sensible", and added: "The decision also appears to lay to rest uncertainty about the future of the SFO, at least for the time being."