A British court on Thursday jailed nine Islamists inspired by slain Al-Qaeda linchpin Anwar al-Awlaqi for planning terror attacks on targets including the London Stock Exchange.

The nine men, who are all Britons of Bangladeshi and Pakistani heritage, had pleaded guilty to a variety of terror-related offences at a hearing a week ago at Woolwich Crown Court in southeast London.

Judge Alan Wilkie sentenced three of the men to "imprisonment for public protection", an indeterminate jail term for suspects regarded as dangerous.

The other sentences ranged from 21 years to five years.

Wilkie said they were "fundamentalist Islamists who have turned to violent terrorism in direct response to material, both propagandist and instructive, issued on the Internet by Al-Qaeda in the Arabian Peninsula."

Awlaqi, the US-born leader of AQAP, was killed on September 30 in an air strike in Yemen.

Wilkie added that it was a "difficult and complex sentencing" that "gives rise to a number of issues of principle and has a high profile."