MOSCOW - An African American exchange student was stabbed by unknown assailants in a southern Russian city in an attack officials say may have been racially motivated.

Stanley Robinson, 18, of Providence, Rhode Island, was in grave but stable condition yesterday at Hospital No. 12 in the southern city of Volgograd, the hospital's head doctor said.

Investigators were trying to determine if the Dec. 5 assault was a hate crime, city police spokeswoman Svetlana Smolyaninova said. No suspects have been detained, and she said authorities had not ruled out robbery or random violence.

Robinson's mother, who has spoken twice with her son by telephone since the attack, said she had no doubts about what motivated the attack.

"I believe it happened because he is a person of color," Tina Robinson said in a telephone interview yesterday from her home in Providence. "It was completely unprovoked."

'Very concerned'

The stabbing took place in Volgograd, an industrial city of one million people 550 miles southeast of Moscow.

Tina Robinson said her son had developed pneumonia, and said she was trying to arrange his transfer to a Western-style medical facility. "I'm very concerned about the care he's getting there," she said.

The U.S. Embassy declined comment, citing privacy concerns.

In recent years Russia has seen a rising number of attacks against members of non-Slavic ethnic groups, particularly darker-skinned migrants from the Caucasus region and Central Asia.

African students and immigrants are also frequent targets of attacks, but attacks on Westerners are rare.

Two Tajik men were attacked in a town north of Moscow last week. One was beheaded and Russian media reported his head was found 12 miles away.

At least 85 deaths

An obscure nationalist group claimed responsibility in an e-mail to the Sova hate-crime monitoring group.

Galina Kozhevnikova, the deputy head of Sova, said at least 385 people had been hurt in racially motivated attacks this year. According to Sova, at least 85 people have been killed in such incidents.

Relatives said Robinson, a graduate of East Providence High School, was three months into his stay. He was studying Russian on a program arranged by the American Field Service.

Tina Robinson said she was unaware of Russia's troubles with racism when her son left for a year abroad. "If I had any inkling that there was any possibility of this happening, I would have tried to dissuade him," she said.