Mr Duggan's shooting sparked unrest which turned into widespread rioting.

BBC: Mark Duggan shooting: Taxi driver 'cannot forget'

Chokri Belaid was shot four times outside his home on the morning of February 6, provoking widespread rioting around the country as many held the government responsible for his death.

NPR: Tunisia: 4 In Custody For Politician's Murder

Nick Pearce, of the Institute for Public Policy Research, speculates that previous bouts of widespread rioting, such as in 1981, demanded a response because they were fuelled by racial grievances.

ECONOMIST: A year after the riots

Egyptians have less emotional attachment to Palestine, but some analysts fear that the country's dire economic problems have sapped public confidence in the government to the point where one serious incident could spark widespread rioting.

ECONOMIST: But there is little they can do

The difficult economic conditions, combined with racial tensions, sparked widespread rioting in Britain's inner cities and made her the ripe target for an emerging generation of musicians such as Elvis Costello and Billy Bragg who were associated with the country's punk movement.

WSJ: Thatcher Was a Skeptic on Centralized Europe

In the last 24 hours there have been disturbing reports of widespread looting and rioting in provincial towns, including Sfax.

BBC: Resurgence of revolt where Arab Spring began