Russian police have begun murder inquiries after the 20-year-old student and a Cameroonian man were stabbed and killed in separate 'racist' attacks in Moscow in recent days, the Ria Novosti news agency said Sunday.

In Hanoi, foreign ministry spokesman Le Dung said Vietnam 'condemned this barbarous act' and said that its embassy in Moscow had 'expressed the deepest concern about this serious event.'

Mr Dung requested that Russia quickly find and punish those responsible and take 'effective measures to ensure the security of Vietnamese' in Russia.

The Vietnamese student, identified as Tang Quoc Binh, died in hospital after being stabbed in his chest Friday night by an unknown attacker in the south of Moscow, a prosecution investigation group said.

'We are examining every aspect of this attack on a foreigner, in particular whether it was motivated by nationalist or racist sentiments,' the group said.

Rights groups in Russia say racist crimes have risen five-fold over the past half-decade. The Moscow Human Rights Bureau says 113 people were killed and 340 wounded in 254 racist attacks in Russia from January to October 2008. -- AFP