Chad sent ground troops into Nigeria for the first time on Tuesday to fight Boko Haram in a sign of increased regional pressure on the Islamist rebels after weeks of surging violence.

The Chadian offensive on the town of Gamboru, which borders Cameroon, follows days of clashes with the Islamists who control vast swathes of northeast Nigeria.

Chadian aircraft on Saturday bombed the Nigerian town of Gamboru in a raid targeting extremist group Boko Haram, security sources said, as regional efforts to combat the Islamists intensified. 

An initial raid was carried out around midday by two fighter jets on the town in Nigeria's far northeast along the Cameroon border, sources from Chad and Cameroon said on condition of anonymity.

Central African nations have rejected a ceasefire deal struck by militia forces from war-torn Central African Republic, Chad's President Idriss Deby said Saturday.

The deal was signed last week in Kenya between senior representatives of the anti-balaka rebels and the ex-Seleka movement of ex-president Michel Djotodia, but without government involvement.

Thousands of Nigerian civilians who fled the armed Islamists of Boko Haram have become a headache for Chadian authorities after seeking safety on a multitude of scattered islands in Lake Chad.

"We waded through the water for several days and suffered so much," recalled former taxi driver Adamou Bouba, who snatched up his toddlers, aged two and three, when Boko Haram fighters raided his village, Kiguili, and killed his wife.

Three soldiers and 123 Boko Haram militants were killed when the Islamist group attacked a Chadian army contingent in northern Cameroon, the Chadian military said Friday.

Twelve soldiers were wounded in the attacks staged by the Islamists on Thursday and Friday near the border town of Fotokol, according to a military statement read out on national television.

More than 14,000 people fleeing Boko Haram violence in northeast Nigeria have streamed into Chad since the beginning of 2015, according to a United Nations report on Wednesday. 

The report by the U.N.'s Office for the Coordination for Humanitarian Affairs (OCHA) put the daily arrivals rate at 774 and said it expected 30,000 refugees to arrive in the country this year.

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."

Chad's parliament voted Friday to send armed forces to Cameroon and Nigeria to fight Boko Haram a day after President Idriss Deby Itno announced his intention to join the fight against the Islamists.

Chad's parliament in N’Djamena voted 150 to 0 to send an unspecified number of "Chadian armed troops and security forces to assist Cameroonian and Nigerian soldiers waging war against the terrorists in Cameroon and Nigeria," a parliament statement said after the vote to join what is now a regional effort defeat Boko Haram.

Cameroon's President Paul Biya announced Thursday that Chad will send troops to aid his country's army fight Boko Haram militants from Nigeria, a government spokesman said.

"Chadian President Idriss Deby Itno has decided to send a substantial contingent of Chadian troops to back the Cameroonian armed forces who have faced repeated attacks from the Boko Haram terrorist sect with courage, determination and vigilance," the Cameroonian spokesman said in a statement.