Osama Bin Laden's replacement as leader of Al-Qaeda is planning a major terrorist attack on London, ordering his followers to 'crush' the city.

Soon after being officially appointed caretaker chief of the terrorist group, Saif al-Adel vowed to avenge the death of his former boss, according to dailymail.co.uk.

“Our new leader has asked for a big plan for London,” Taliban spokesman Ehsanullah Ehsan said. “He believes the UK is the backbone of Europe and must be crushed.”

Taliban and Al-Qaeda leaders met near Pakistan's border with Afghanistan to confirm the new role for al-Adel, 51, who was once Bin Laden's security chief, The Sun reported.