GOMA, Congo (AP) — Rebels believed to be backed by Rwanda fired mortars and machine guns Monday in a village on the outskirts of the provincial capital of Goma and threatened to attack the city which is protected by ragtag Congolese government troops backed by United Nations peacekeepers.

The gunfire and explosions erupted in the early afternoon, hours after the M23 rebels said they were halting fighting in order to negotiate with the government of Congo. Government spokesman Lambert Mende told The Associated Press by phone that negotiations are out of the question, saying Congo will not give in to the "blackmail" of a Rwandan-backed group.

Civilians including young children ran to safety when the fighting resumed. In Goma, a city of 1 million, civilians sought shelter in huts and behind ledges alongside a main road as tanks rumbled by.

Earlier, M23 rebel spokesman Col. Vianney Kazarama told the AP that his men were on their way back to Kibumba, 30 kilometers (18 miles) north in order to give proposed talks a chance. But on Monday afternoon, Kazarama blamed Congo for renewed hostilities and once again vowed that M23 would take Goma.

"The army provoked us. They have fired on our men ...We are going to take Goma tonight," he said.

A major U.N. peacekeeping base is in Goma. On Saturday U.N. attack helicopters targeted M23 positions. U.N. peacekeeping chief Herve Ladsous said the rebels are very well-equipped, including with night-vision equipment allowing them to fight at night. U.N. spokesman Kieran Dwyer said Sunday that 17 U.N. "quick reaction units" have been deployed throughout Goma.

"The situation in Goma is extremely tense," Dwyer said on Sunday. "There is a real threat that the city could fall into the M23's hands and/or be seriously destabilized as a result of the fighting."

M23 began when several hundred men led by Gen. Bosco Ntaganda — who is wanted by the International Criminal Court —defected from the Congo army in April. Congo analyst Jason Stearns, a former member of the United Nations Group of Experts, said on his blog that the group is now believed to be composed of 2,500 to 3,000 men.

The situation mirrors events in 2008, when a now-defunct rebel group known as the National Congress for the Defense of the People, or CNDP, advanced to the edge of Goma as some Congolese government dropped their weapons and ran. That group, which was financially and militarily backed by Rwanda, stopped just short of taking the city. The rapid advance forced the government to enter into negotiations with the rebels. The peace deal brokered on March 23, 2009, called for CNDP fighters to be integrated into the national army.

Tellingly, the new rebel group's name comes from the date of those peace accords, which the M23 says were never fully implemented by the government. M23 fighters include former members of the CNDP. The M23 rebels told the government to make a declaration on state TV and radio announcing the start of negotiations, but did not state what they hope to achieve in talks. The U.N. Group of Experts says M23 is believed to be backed by neighboring Rwanda, which the Rwandan government of President Paul Kagame denies.

Observers say it is in Rwanda's interest to exert influence over areas of eastern Congo bordering Rwanda, where Hutus fled after perpetrating the 1994 genocide inside Rwanda against mostly Tutsis. Exerting influence would enable Rwanda to maintain a buffer zone and to exploit the trade and trafficking of minerals in eastern Congo.

In a statement released on Monday, the M23 called for the immediate demilitarization of the city and the airport in Goma, and for the opening of the border at the town of Bunagana within the next 48 hours.

Reports by Human Rights Watch as well as by the U.N. Group of Experts indicate that Rwanda is providing arms, logistical help and even soldiers to M23.

Over the weekend, U.N. Secretary-General Ban Ki-moon called the Kagame to ask him to intervene and stop the M23 offensive, according to a statement issued at U.N headquarters in New York.

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Callimachi contributed from Dakar, Senegal. Associated Press writer Saleh Mwanamilongo contributed to this report from Kinshasa, Congo.