Russian police have arrested a suspect in the killing of a student from Senegal last week - the latest in a series of attacks against foreigners and dark-skinned people in Russia. Criticism has been leveled at the authorities for failing to take strong action to confront the problem, amid signs that the issue is also being exploited for political reasons.

Russian prosecutors have detained a suspect in the killing of 28-year-old Lampsar Sall, a fifth-year student at the State Communications University in Saint Petersburg.

Sall was shot in the neck as he left a popular nightclub with some friends, early Friday morning.

Police found a swastika painted on the murder weapon and, within hours, a neo-Nazi website applauded the murder, stating that "the clean-up of the city continues".

Sall's death was just the latest in a long series of incidents targeting Africans, Asians and non-Slavic peoples from inside Russia or other ex-Soviet republics.

Just two weeks ago, a girl of mixed Russian and African origin was wounded in a knife attack in Saint Petersburg, which has gained a reputation as the Russian city with the highest number of such incidents.

In one of the worst cases there, a nine-year-old girl from Tajikistan was beaten to death by skinheads, while walking with her family, two years ago.

Police have long been criticized for treating many such cases as acts of hooliganism, which carries a much lighter sentence when the perpetrators are arrested, which is not always the case.

So far this year, there have been seven killings and scores of injuries attributed to racist attacks, according to the SOVA Analytical Information Center in Moscow. There were 27 killings, last year.

Lyudmila Naruseva, a member of the Federation of Science, Culture, Education and Health in Saint Petersburg, asks how much more blood will be shed on city streets and how many more young girls will be attacked and killed. She calls for action against racism and fascism.

President Vladimir Putin has told security agencies they must step up their efforts to combat what he calls "militant nationalism and xenophobia."

Analysts say economic hardship and a sense of inferiority among young Russians account for much of the problem.

But there is also a political dimension in the run-up to parliament and presidential elections in two years.

Nikolai Petrov, a political analyst in Moscow, says this is not the first time politicians are playing the nationalist card.

He says what he calls "the central power" is using what he terms "the brown threat" to effect elections.

Russia has two nationalist parties in parliament, including one led by Vladimir Zhirinovsky, known for statements many see as racist and anti-Semitic.

The second party got into trouble with the authorities last year, when it ran a television advertisement that called people from Azerbaijan "garbage."

Alexei Malashenko, who is with the Carnegie Center in Moscow, says the nationalist threat may also have an anti-Western aspect.

"Nationalism can be used for a kind of national idea, maybe turned against the West," he said. "It may perform a role or certain instrument for social consolidation. But, I think that in the future the activity of Russian nationalists may present a big danger for Russian political establishment."

Concern is now growing among the general public because of various high-profile cases.

In Moscow earlier this month, youths beat a television journalist from the southern Caucasus Mountain region.

Suspected skinheads in Moscow also severely wounded a prominent singer who is the culture minister of Kabardino-Balkaria, a republic in the Caucasus.

All of this adds to a climate of fear among the immigrant, foreign and student communities in Russia.

Back in Saint Petersburg, friends of Lampsar Sall gathered in their dormitory to discuss the situation. One asked the question that is likely to be on all of their minds: "Who might be next?"