Police have moved to reassure residents in a city labelled the worst for sex attacks that they face a "minimum risk" of being raped by a stranger.
The report said Portsmouth had the highest rape rate
Portsmouth was labelled by think tank Reform as the city with the highest numbers of rapes per 1,000 people.
Ch Supt John Campbell, of Hampshire Constabulary, said 70% of victims in the city knew their attacker and most attacks did not happen on the street.
The number of rapes reported might be due to successful police work, he said.
WORST PLACES FOR CRIMES
Vehicle crime: Nottingham
Gun crime: Bradford
Source: Reform report
"Police in Portsmouth welcome today's report by the Reform think tank, but wish to reassure residents that they are at a minimum risk of street attacks for this offence," he added.
"Statistics show that 70% of rape victims know the offender. The vast majority of rape offences - 86% - happen in private, and 11% of offenders are ex-partners or boyfriends.
"Police in Portsmouth have worked closely with partner agencies and the city council to develop a climate where victims feel confident to report rape, which is generally an under-reported crime.
"This work by police and other agencies has been successful, which probably accounts for the high number of reports of rape in the city," he said.
The report, released on Tuesday, labels Nottingham as the most crime-ridden place in England and Wales.
The survey ranked urban areas with populations of more than 100,000 using data on burglary, murder, rape, robbery, car and gun crime from police.
It gathered statistics from police forces using the Freedom of Information Act and took population data from the 2001 Census.