Russia's second city saw a wave of apparently racially motivated attacks on non-Russians earlier this year, but Valentina Matviyenko said they were not proof the city as a whole disliked foreigners.
"Mass xenophobic sentiments are non-existent [in the city]," Matviyenko told reporters, adding that St. Petersburg residents were offended by attempts to label their city as a capital of xenophobia.
Matviyenko said the group behind a series of recent attacks on foreigners in St. Petersburg, which is to host a summit of the Group of Eight leading industrialized nations in July, had been arrested.
St. Petersburg Prosecutor Sergei Zaitsev said earlier that an eight-member extremist gang suspected of being involved in the killing of a student from Senegal and other crimes had been broken up.
Zaitsev also said the gang had been involved in the killing of a Korean national in 2003 and a senior official at the local anthropology and ethnography museum, the Kunstkamera, in June 2004.
Matviyenko also said the group had been linked to a similar gang dealing in Moscow.
"I do not mean to say that [the gang's] action was controlled from Moscow, but it did have links to similar groups in Moscow. I am familiar with the case files and can say that the group had been committing those crimes, timing them to coincide with the summit," she said.
St. Petersburg has been beset by negative publicity over alleged neo-Nazi attacks and killings, which also include the beating of a Chinese student, and the stabbing of a nine-year-old girl of mixed Russian-African origin in early 2006.
Other violent attacks on non-white foreigners in St. Petersburg in recent months include an attack on a man from Mali, who was stabbed to death in February, and the murder of a student from Cameroon last December and of a Congolese student in September.
Routine attacks by skinheads and youth gangs on foreigners and people with non-Slavic features have also been reported in other Russian cities.