An earthquake with a magnitude of 4.6 hit an area around the northwest Iranian city of Tabriz on Saturday frightening residents when some power and telephone lines were cut in the city, the official IRNA news agency said.

The disruption to services in a large part of the city sent many people into the streets in panic, some taking to their cars and causing heavy traffic, IRNA reported.

Downed phone lines made it difficult for officials to contact the affected area to determine possible damage, IRNA said.

It did not immediately give any other reports of damage or casualties. It said the 4.6 magnitude quake at 10.15 p.m. (1845 GMT) followed a 3.9 tremor less than half an hour earlier.

Earthquakes regularly strike Iran, the world's fourth largest oil producer which is criss-crossed with fault lines.

The northwest city of Tabriz is not close to major oil producing areas, which are mainly in the southwest and south of Iran, near the Gulf.