Tens of thousands of people rallied in the capital of Chad on Saturday in support of the authorities' decision to send troops to fight Nigeria's Boko Haram Islamists.

Prime Minister Kalzeube Pahimi Deubet led the demonstrators as they marched from city hall in the capital N'Djamena to the Place de Nation square, carrying Chadian flags and chanting in French and Arabic: "Kick the forces of evil out of our territory."

Tens of thousands of people rallied in the capital of Chad on Saturday in support of the authorities' decision to send troops to fight Nigeria's Boko Haram Islamists.

Prime Minister Kalzeube Pahimi Deubet led the demonstrators as they marched from city hall in the capital N'Djamena to the Place de Nation square, carrying Chadian flags and chanting in French and Arabic: "Kick the forces of evil out of our territory."

In his first prominent speech since telling donors last week he was still interested in the White House, the 2012 Republican nominee hinted and quipped about a possible presidential run next year but stopped well short of any announcement.

With the 2016 election cycle clearly underway and Jeb Bush announcing last month that he is actively exploring a presidential bid, Romney suddenly finds himself under political pressure to signal whether he is ready to mount a third campaign to lead the nation, or yield to a new crop of candidates.

Nigeria's President Goodluck Jonathan paid a surprise visit Thursday to the heartland of the Boko Haram movement after satellite pictures  showed massive destruction in two northern towns razed by the Islamist fighters.

Jonathan spent three hours in Maiduguri, capital of Borno State, meeting with survivors of what is thought to be the worst attack in Boko Haram's six-year insurgency.

U.S. Secretary of State John Kerry branded a Boko Haram massacre in northern Nigeria a "crime against humanity" Thursday as satellite images suggested massive destruction in the two towns reported razed by its fighters.

"What they have done... is a crime against humanity, nothing less," Kerry said as first images of what is feared to be the worst atrocity of the six-year Islamist insurgency emerged.

Nigeria's military on Wednesday said that soldiers had repelled a new Boko Haram attack after a two-hour gun battle in the restive northeast.

The country's defence headquarters said in a series of tweets that the militants had been pushed back from Biu, in Borno State, and two anti-aircraft guns had been captured.

The United States on Tuesday urged Nigeria to go forward with planned February 14 presidential and legislative elections, despite being hit with "horrific" attacks by Islamist group Boko Haram.

The State Department declined to give any specific figures Tuesday for the number of victims in an offensive by the group in the northern region of Baga, on the banks of Lake Chad.

Nigeria's electoral agency said Tuesday that next month's elections will go ahead in three northeastern states worst hit by Boko Haram violence but there was little prospect of voting in militant-held areas.

"INEC (Independent National Electoral Commission) has always said that it is preparing to conduct elections in all the 36 states and the Federal Capital Territory, including the three northeast states experiencing the challenge of insurgency," said the body's chairman, Attahiru Jega.

A suicide bomber was killed on Tuesday when his explosives vest detonated as he rode towards a security checkpoint in the northeast Nigerian city of Gombe, witnesses told AFP.

A huge explosion rocked the Kasuwar Mata area of the city around 6:30 pm (1730 GMT) while most residents of the mainly Muslim city were at evening prayers.

The United Nations on Tuesday said that the latest wave of Boko Haram's "vicious, ruthless attacks" in northeastern Nigeria had sent 11,320 people fleeing into Chad in a matter of days.

The Islamist group stormed the town of Baga on January 3, and subsequently razed it and at least 16 surrounding settlements.