FBI director Robert Mueller says leadership skills are the key

He made the statement as he testified in an employment discrimination lawsuit brought by FBI agent Bassem Youssef.

Mr Youssef claims he was passed over for promotion despite his notable knowledge of counter-terrorism.

Following the 11 September attacks in Washington and New York the FBI vowed to increase its terrorism expertise.

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After the 2001 attacks, senior officials at the FBI admitted that their knowledge of international affairs, notably in Arab countries, of the Arabic language and how to combat the potential threat from Islamic extremists had been flawed.

However, Mr Mueller testified that he was against demanding that managers had knowledge in those areas.

Leadership ability is transferable and often you can pick up the subject matter if you've got leadership skills Robert Mueller

Mr Mueller also testified that in the immediate aftermath of the attacks he did not instruct his managers to ensure that agents with the most experience of counter-terrorism were put to work on the war on terror.

"It was in their hands as to how they did that,'' Mr Mueller said.

Lack of knowledge

Mr Mueller said that when he took over as director of the FBI in 2001, just a week before the 11 September attacks, his knowledge of Middle Eastern terrorism had been "relatively limited".

The FBI's executive assistant director in charge of terrorism, Gary Bald, also testified recently, telling Mr Youssef's employment lawsuit that he had got his training in fighting terrorism when he took on the job two years ago.

He also admitted that he had little or no knowledge of Middle East affairs.

"I wish that I had it. It would be nice," he said.

When questioned on Mr Bald's statements Mr Mueller argued it was incorrect to say he had been forced to learn on the job as he had been the head of the FBI's Baltimore office during the Washington sniper shootings in 2002.

"Running the office gave him some exposure to terrorism," Mr Mueller said.

Attention elsewhere

Mr Mueller argued that leadership skills, not background knowledge, were the most important factor in deciding who should run the war on terror.

"Leadership ability is transferable,'' Mr Mueller said. "And often you can pick up the subject matter if you've got leadership skills.''

Mr Youssef's lawsuit claims that he has been unfairly passed over for promotion a number of times despite having greater experience in counter-terrorism than the other candidates.