With their bright red jackets and berets, the Guardian Angels were once a common sight in a city riddled with violent crime. 

And this week they made a pointed return to New York's Central Park for the first time in more than two decades, citing a 26 per cent rise in crime there so far this year. 

"We realise things are much better than they were" in the crime peak of the 1980s and early 90s, said Curtis Sliwa, the group's founder, but "we want it to stay that way." 

City officials stress that crime is down citywide, and the park is far safer than it once was. Still, the renewed patrols by the Guardian Angels - known for both crime-fighting and controversy during their 35 years - are bright-red signals of unease about whether New York, touted for years as the nation's safest big city, is slipping.