Kinshasa - Up to 12 people have been killed in a series of night-time shootings and grenade attacks in the Democratic Republic of Congo city of Goma, raising fears rebels from the surrounding countryside have started a new offensive, officials said.
Witnesses told Reuters on Thursday youths equipped with torches and whistles had started organising watches to protect their neighbourhoods after dark and panic was spreading.
"For the past two weeks we have seen scores of killings, attacks with guns, lootings, illegal entering into NGO (aid group) houses, I can't even count them," said Alexander Essome, the Goma-based spokesman for the United Nations peacekeeping mission MONUSCO.
Goma is the capital of North Kivu, which has been swept by violence since March when hundreds of soldiers defected from the army in support of mutinous general Bosco Ntaganda, wanted by the International Criminal Court for suspected war crimes.
Rebels have been trying to take control of large parts of the east of the country and seizing Goma would be a major coup.
Three people, including a presidential guardsman and a local woman, were gunned down in Goma on Monday night, said Ernest Kyaviro, spokesman for the provincial governor.
A grenade was also thrown at the car of the vice governor of North Kivu on Wednesday, though he was not in the vehicle at the time, he added.
"It's been going on for a week, and to my knowledge 12 people have been killed," Kyaviro said. "I think there is an infiltration of the city by M23 who are carrying out these terrorist acts," he said, refering to the M23 rebel group, which is currently holding positions about 30 km (19 miles) from Goma.
Goma is also home to thousands of aid workers, helping deal with the aftermath of decades of conflict in the country.
One western aid worker who asked not to be named told Reuters several vehicles belonging to international organisations had been attacked in recent weeks and people were afraid to move around after dark.
The United Nations says the rebel force is receiving support from neighbouring Rwanda, an accusation dismised by Kigali.