Rescue workers on Wednesday combed through the rubble of Nigeria's deadliest bomb attack after at least 118 people were killed in the central city of Jos, with Boko Haram blamed for the atrocity. Emergency services picked through the burnt-out remains of vehicles and collapsed buildings in the New Abuja Market area of the city, where two car bombs exploded within 20 minutes of each other on Tuesday. The attack was the latest affront to the Nigerian government's internationally backed security crackdown in response to the mass abduction of more than 200 schoolgirls on April 14 that has sparked global attention. Two more attacks in villages near the girls' hometown of Chibok in northeastern Borno state were meanwhile reported, with witnesses saying that 30 people were killed on Monday and Tuesday. In Jos, where Boko Haram have attacked before, Plateau state governor Jonah Jang's spokesman said the bombing bore the hallmarks of the Islamist extremists. "This is not a Berom-Fulani attack," Pam Ayuba told AFP, referring to the long-standing ethnic violence between Christian farmers and Muslim herdsmen that has claimed tens of thousands of lives in the region in the last two decades. "The investigation is still ongoing but this is clearly an extension of the terrorist activity that has affected the northeast of the country, the Boko Haram insurgents." Kyari Mohammed, a Boko Haram specialist and chairman of the Centre for Peace Studies at Modibbo Adama University in Yola, Adamawa state, also blamed the Islamists. "They're the only ones capable of doing this. Every other rebel or fringe group can use bombs but not of this scale or sophistication," he said. "I have the feeling that what they want to achieve is to escalate things because of the international pressure which has built up (because of the kidnapping)." On the day of the mass abduction, Boko Haram launched a car bomb attack on a bus station in a suburb of the capital Abuja which killed 75 and are suspected of a copy-cat attack in the same location on May 1 which left 19 dead. Four people were killed in a suicide car bomb attack in the northern city of Kano on Sunday, although it was unclear whether the attack was linked to Boko Haram, despite the militants having attacked the city before. - Death toll may rise - Rescue workers were among those who were caught up in the Jos bombings. As they tended to the injured from the first blast, the second detonated. Improvised explosive devices were hidden in a minibus and truck, the military said. Nigeria's National Emergency Management Agency (NEMA) said late on Tuesday that 118 were killed and 56 injured but warned that the death toll could rise further. "Our director-general is on his way to the scene now," NEMA spokesman Manzo Ezekiel said on Wednesday. "He and his team will carry out a rapid assessment of the situation and then we will be able to estimate the losses that we incurred. "So, for now, we are holding at 118 (dead) but there is a likelihood of some changes." Nigeria and its President Goodluck Jonathan have been criticised for their slow response to the Chibok kidnapping as well as their overall response to the five-year insurgency that has claimed thousands of lives. The international attention on the plight of the missing girls has seen specialist teams from the United States, Britain, France and Israel sent to Nigeria to help in the search effort. - Escalation of violence - Parliament on Tuesday approved a request for a further six-month extension of a state of emergency in Borno and neighbouring Yobe and Adamawa states with the caveat that non-military means should also be explored to end the violence. Jonathan is adamant that there will be no negotiations with Boko Haram on swapping the girls for militant fighters held in Nigerian jails but the government has maintained it is open to dialogue on wider issues. In New York, Nigeria submitted a request to the United Nations to proscribe Boko Haram as an international terrorist group, while the country's neighbours have vowed to step up co-operation to prevent a regional conflagration. Mohammed, however, said that while on the one hand international pressure was forcing the government in Abuja to act, it was also emboldening Boko Haram to mount further strikes. "They have sleeper cells all over the northern part of the country and they're activating them. That's what they're going to do," he said. "We should anticipate more attacks, especially if they (the government and the international community) are unable to solve the Chibok problem... "If they have allies across the Sahel or beyond they can get more support... We have succeeded in giving them the kind of profile that they didn't have. They are now a bigger player."