MADALLA, Nigeria (AFP) - Nigerian President Goodluck Jonathan on Saturday described the Boko Haram Islamist sect blamed for hundreds of deaths as a "cancerous" body that was bent on destroying the country.
But he vowed the group would be foiled.
"(Boko Haram) started as a harmless group... they have now grown cancerous," he said. "And Nigeria, being the body, they want to kill it. But nobody will allow them to do that."
Jonathan was speaking on a visit to a Roman Catholic church in Madalla, near the capital Abuja, where 44 people leaving a mass were killed in a Christmas Day bombing claimed by the group.
It was the bloodiest in a wave of attacks on Christmas Day that killed a total of 49 people in Madalla and elsewhere in the north of Africa's most populous country.
"Some people are exploiting it (the situation) to their own advantage. But a terrorist attack on any part of the nation is an attack on all of us," Jonathan said.
"Collectively, we will bring it under control and finally crush it," he said. "As president and commander-in-chief of the Federal Republic of Nigeria, I will take action and this unrest must come to an end very soon."
Observers described his comments as the toughest in recent times against the sect -- whose name means "Western education is sin" in local dialect -- and its operations since 2009.
During his address in the church, many worshippers cried uncontrollably, including two women who lost their husbands and four children in the Christmas Day bombing.
Jonathan, who first took office in May 2010, said he would address the nation on television later Saturday to reveal some of the measures his government will take to tackle the group.
Madalla is part of the Suleija municipality, a major city in Niger State located some 40 kilometres (25 miles) outside Abuja.
"All the terrorist attacks in Niger State are taking place in Suleija. We are going to turn this local government upside down," he warned.
He said if there were institutions or individuals in the city that were harbouring criminality "we are going to deal with them decisively. There will be no sacred cows".
Two former Nigeria's head of state -- Ibrahim Babangida and Abdulsalami Abubakar -- hail from the state, where the nation's major hydro-electric power station is located.
An influential body grouping Nigeria's Catholic bishops on Saturday urged Jonathan to hire foreign crime experts to help wipe out the Boko Haram.
"I call on Mr President to recall the retired experts in criminology and employ foreign experts in this field to assist the active security agents to put an immediate end to the Boko Haram menace," the president of the group, Archbishop Felix Alaba Job, said in a statement.
Christian leaders have expressed mounting frustration over the authorities' inability to stop the attacks, most of which have occurred in the northeast but also included the August suicide bombing of UN headquarters in Abuja that killed at least 25 people.
While Boko Haram initially sought the creation of an Islamic state in the north of Nigeria, some people claiming to speak on its behalf have since issued a range of demands.
There has been intense speculation over whether it has formed links with outside extremist groups, such as Al-Qaeda's north African branch and Somalia's Shebab rebels, although no operational connections have been proven.