Osama bin Laden has appointed a new commander to spearhead al-Qaeda's offensive of operations against the West.

Known to western intelligence services by the alias Saif al-Adel, or "Sword of the Just", al-Qaeda's new chief of international operations is believed to have conceived of the wave of strikes that set off terror alerts across Europe recently, as well as last week's mid-air parcel-bomb plot.

US and Pakistani sources have told The Daily Telegraph that al-Adel is running several similar operations as part of a war of attrition intended to persuade Western public opinion that the war against terror is unwinnable. This would clear the road for al-Qaeda to capture power in fragile states such as Somalia and Yemen.

A US counter-terrorism official said the idea was for "small-but-often attacks" that would hurt the West more than a "one-off terror spectacular".

In 2005, al-Adel authored an al-Qaeda planning document that holds clues to his thinking. The document said that Islamist movements failed because their "actions were mostly random". It called for al-Qaeda to focus on "the greater objective, which is the establishment of a state". The new attrition strategy marks the triumph of a minority faction within al-Qaeda who had opposed the 9/11 attacks, arguing that the inevitable US retaliation against Afghanistan would cost the jihadist movement its only secure base.

In 2002, jihadist internet forums carried a letter purported to have been written by al-Adel, criticising bin Laden's leadership. Little was heard of al-Adel, who was held by Iran with a group of al-Qaeda fugitives, for several years thereafter. The fugitives were housed in villas along Iran's Caspian coast and in Lazivan, north-west of Tehran. Al-Adel lived there with his five children and wife Wafa, who is the daughter of Mustafa Hamid, another top al-Qaeda figure.

But in April this year, he was released from Iranian custody along with Saad bin Laden, Osama bin Laden's son, and top al-Qaeda operatives Suleiman al-Gaith and Mahfouz al-Walid.

Iran swapped the terrorists for Heshmatollah Attarzadeh, a Pakistan-based diplomat kidnapped by al-Qaeda last year.

Little is known about the shadowy al-Adel, who is also known by the names Muhammad al-Makkawi and Ibrahim al-Madani. Born in Egypt, al-Adel is said to have served as a colonel in its Special Forces. He was, however, arrested in 1987 along with several jihadists.

Egyptian prosecutors claimed that al-Adel's plans included crashing an aircraft into the Egypt's parliament, or driving a bomb-laden truck into the building — both tactics al-Qaeda later used to devastating effect.

Later, documents filed by US prosecutors show, al-Adel worked as an instructor at al-Qaeda camps in Afghanistan and Somalia, and participated in several attacks. In 2000, Austrian investigators found he played a key role in a plot to assassinate Joseph "Diamond Joe" Hicks — a mining magnate who is also a leading member of a religious Jewish group.