LONDON — Britain's spy agency chief stepped out of the shadows with an unprecedented public address Thursday, defending the need for secrecy to counter growing terror threats such as Iran's nuclear proliferation.MI6 chief John Sawers said even though Cold War-era secrecy has been lifted and intelligence agencies were working to become more accessible keeping intelligence material secret was vital to protect people against terror attacks.RELATED:Iran rejects as 'diabolical' WikiLeaks disclosures Ben-Ari asks UN to probe US for war crimes 'UK spies blew up ships to keep Jews from Palestine' "Secrecy is not a dirty word. Secrecy is not there as a cover-up," Sawers told a select group of journalists in London. "Without secrecy there would be no intelligence services, or indeed other national assets like our special forces. Our nation would be more exposed as a result." The question of secrecy has dominated world news in the last week, after the whistle-blowing group WikiLeaks published nearly 400,000 US intelligence logs detailing daily carnage in Iraq since the 2003 US-led invasion.Some of the leaked documents showed that coalition forces handed over terror suspects to Iraqi security services even after abuse was suspected, or continued with interrogations despite visible injuries to suspects. There has been no clear mention of MI6 involvement in the logs, however.Sawers' speech also came as two government inquiries are probing whether MI6 and other agencies were complicit in the abuse of terror suspects — allegations that Sawers denied Thursday, adding that MI6 agents are obligated by law to stop and avoid torture."And we do —even though that allows terrorist activity to go ahead," he said, adding that although his agency hasn't been specifically accused of torture it has been accused of "being too close to it." Sawers said progress had been made in Afghanistan and Pakistan, but new terror threats were growing in Yemen, Somalia and North Africa."We get inside terrorist organizations to see where the next threats are coming from," he said. "What we do is not seen."He said while a "typical" terror attack would not bring down Britain, the dangers of nuclear proliferation — as well as chemical and biological weapons — had the potential to alter the political balance of power in the region."The revelations around Iran's secret enrichment site at Qom were an intelligence success," he said. "They led to diplomatic pressure on Iran intensifying, with tougher UN and EU sanctions, which are beginning to bite."But using intelligence poses anguishing choices for agents — especially when faced with the possibility that intelligence could be tainted by abuse or torture."Suppose we received credible intelligence that might save lives, here or abroad. We have a professional and moral duty to act on it," he said."We also have a duty to do what we can to ensure that a partner service will respect human rights. That is not always straightforward. If we hold back, and don't pass that intelligence, out of concern that a suspect terrorist may be badly treated, innocent lives may be lost that we could have saved," he said. "Sometimes there is no clear way forward."MI6, known as cloak-and-dagger employer of the fictional James Bond, has tried to become less secretive. It has started posting recruitment ads in Britain's media, hired press officers, and last month released its first-ever official history. But Britain's three major intelligence agencies collectively face a 7.5 percent cut over the next five years.Insisting that intelligence was more important now than ever, Sawers said MI6 would be working closely with Britain's domestic spy agency, MI5, and its eavesdropping agency, GCHQ, on budget issues."Yes, the intelligence services have to make savings too," he said.