Some 64 cities are categorised as "extreme risk" by Verisk Maplecroft, which advises business on risk management. Five cities in Iraq are most at risk, with Baghdad enduring 380 terrorist attacks, which led to 1,141 deaths and 3,654 wounded.
Bristol ranked higher than LondonIn the UK, Belfast is at highest risk (91 in the list), while Bristol (179), Cardiff (314) and Manchester (399) are ranked higher than London (401).
This is because Bristol and Cardiff have suffered attacks by anarchists and far-left radicals in recent years, while London - scene of the 7/7 bombings in 2005, in which 52 people were killed - has been relatively quiet. But they are at low risk in international terms.
In February 2014, three military vehicles in Bristol were destroyed in an arson attack claimed by a group called the Informal Anarchist Federation IAF). The IAF has also been linked to attacks on politicians' homes, the destruction of a broadcast mast and the sabotaging of train lines in the Bristol area.
There have been more than 100 anarchist attacks in the Bristol area over the last the last two years, but no-one has been killed.
AnarchistsCharlotte Ingham, from Verisk Maplecroft, said: "Despite low-level attacks by anarchists and left-wing radicals in cities including Bristol and Cardiff, commercial centres, above all London, remain the primary focus of Islamist militant groups looking to commit a large-scale terrorist attack in the UK.
"London's low level of risk in the index reflects the success of the British security services since the 7/7 attacks in preventing any further significant incidents."