In a speech on intelligence and security to the Royal United Services Institute (RUSI), Hammond said the exposure of so-called "Jihadi John" had led to some seeking to excuse his role in beheadings of hostages by pointing the finger of blame at intelligence agencies.
Hammond said: "The exposure of the alleged identity of one of the most murderous ISIL (Islamic State) terrorists over the last few weeks has seen some seeking to excuse the terrorists and point the finger of blame at the agencies themselves".
"Britain's MI5 had come under attack over their handling of Londoner Mohammed Emwazi, or "Jihadi John", as it emerged he had been on their radar but they failed to prevent him joining IS in Syria," he added.
"We need to go on backing the agencies with the resources they need to fulfil their vital mission," Hammond said.
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We work through our long term economic plan to undo the damage of the Great Recession and ensure we have a growing economy to fund our public services, he said.
He also made a reference to the recent case of the three teenage London schoolgirls believed to have travelled to Syria to join IS, saying it showed there were "things we can improve".
"I think this particular case, of the three school girls from east London, has identified some weaknesses, some things we can improve, but it's also identified some steps people in the community have to take to keep us safe as well," the Foreign Secretary said.