MOSCOW, October 20 (RIA Novosti) - Seven cars were set alight overnight in various parts of Moscow in what police believe is part of a continuing wave of arson attacks on vehicles in the city, a police source said on Monday.

According to the source, three cars were set alight in the north, northeast and southwest of Moscow. Four more cars were damaged during a fire attack on garages in the northwest outskirts of Moscow.

"In each case police and firefighters at the scene of the fires found evidence of suspected or clear arson," the source added. Investigators are currently at the scene establishing the cause of the fire.

Witnesses said a suspicious person had been seen in the area just before a taxi was torched. Investigators also said the car window of another vehicle had been smashed. There was also evidence that a garage had been broken into.

Moscow saw a wave of arson attacks on vehicles parked outside apartment blocks which began on May 30. Over 70 cars were torched in the city during a two-month period in what is believed to be the work of an infamous "car arsonist."

Moscow police earlier circulated a reward of up to a million rubles (about $42,000) for information leading to the arrest of the arsonist or arsonists. Several people were detained in connection with the fires, but later released. No one was charged.