Moscow - The mayor of a town in north-western Russia has been stabbed to death by an unknown attacker, news agencies cited a police source as saying Wednesday.

"An unidentified person ran up to the mayor as she was leaving her house, stabbed her in the neck and fled the scene," the source said.

The motive for the attack late Tuesday evening was unclear, the security source said.

A suspect, who had earlier worked with the Kandalaksha mayor, Nina Varlamova, in the local government, has been detained, local police said.

Varlamova took office in December 2007 after the previous mayor of the Northern Russian town was jailed for corruption, news agencies reported.

Kandalaksha is a city of about 40,500 people in the Arctic circle some 280 kilometres south of the port city of Murmansk.

Varlamova is third Russian mayor to be killed in less than one month. The other two murders took place in Russia's restive Caucasus region of Ingushetia and North Ossetia. (dpa)