Abuja: At least 52 people, including women and children, have been killed in clashes between two rival ethnic groups in southeastern Nigeria, as President Goodluck Jonathan declared a state of emergency in four states to crush the cancerous growth of Islamist insurgency.

A Nigerian government spokesman said the violence in the state of Ebonyi took place between the Ezza and Ezilo peoplesdue to a land dispute.

Local media reported that 52 people, including women and children, were killed in the resurgence of the Ezza/Ezillo inter-communal strife in Ebonyi.

It said a divisional police officer, children and women were among those killed.

The attacks came hours after a state of emergency was declared in parts of the country by President Jonathan due to an unrelated spate of attacks by Islamist group Boko Haram.

The president, in his national broadcast, said it had become necessary to take the step in the light of "recent events in some parts of the country that have threatened our collective security and shaken the foundations of our corporate existence as a nation."

"Consequently, I have... declared a state of emergency in the following parts of the federation," he said, listing parts of the states of Borno, where Boko Haram traditionally has its base, as well as Yobe, Niger and Plateau.

Jonathan's decision came after he visited St. Theresa's Catholic Church, Madalla, Suleja, where some 47 worshippers were killed in a bomb attack on Christmas day, said he was poised to end the reign of terror in the country.

There is growing concern that Boko Haram - whose name means "Western education is forbidden" - is spreading its presence across the region. The sect wants to impose Islamic Shariah law in Nigeria, Africa's most populous nation.

Emergency laws would all allow security agencies to make arrests without proof and conduct searches without warrants. The President also ordered the closure of international borders near the affected areas.

Jonathan said the security forces would take necessary action concerning the affected areas and announced setting up of a counter-terror group within the armed forces to handle the issue of terrorism.

"Terrorism is a war against all of us," Jonathan said as appealed to all Nigerians to join hands with government to fight the terrorists.

"What began as sectarian crises in the northeastern parts of the country has gradually evolved into terrorist activities in different parts of the country with attendant negative consequences on our national security," Jonathan said.

Jonathan had described the Boko Haram sect as "cancerous" and asserted that any attack on any part of the nation was "an attack on all of us".

A suicide bomb attack by the group at the United Nations headquarters in Abuja in July last year had killed 26 persons.

Nigeria, with a population of 150 million, has both Muslim and Christian communities. Muslims are predominant in the north while Christians mostly live in the South.