Armed forces from Chad and Niger have teamed up to launch a fresh offensive against Islamist militant group Boko Haram in Nigeria.
Troops entered the country through southeast Niger and attacked militants in Nigeria's Borno State.
It comes after Boko Haram pledged allegiance to Islamic State, which has taken over parts of Iraq and Syria.
Niger's army repelled an attack by Nigerian Islamist group Boko Haram on the border town of Diffa today, but fierce fighting raged at a nearby bridge that crosses over into Nigieria, military sources said.
A local resident said a bomb had exploded in Diffa's central market, but most locals had already left the streets because of the fighting, which began overnight. A death toll was not immediately available.
At least three more people have been found dead after the latest violent Charlie Hebdo protests in the capital of West African country Niger, bringing the death toll to eight following two days of violence.
Police sources said two charred bodies were found inside a burned church in the outskirts of Niamey, while the body of a woman was found in a bar.
They said she was believed to have asphyxiated from tear gas and smoke.
A police officer and four others have been killed during protests in Niger over French newspaper Charlie Hebdo's cartoons of the Prophet Mohammed.
At least two churches were burned and a police station and the home of a foreign minister were attacked. One body was discovered in a burned out Catholic church.
The French embassy has warned its citizens not to go on to the streets for fear of reprisal attacks.
Police said they had arrested four Muslim preachers in the capital city Niamey.
At least two churches have been torched in Niger as violent protests against the depiction of Mohammed in Charlie Hebdo continue.
Four people are known to have died during demonstrations in the country so far, while police fired tear gas at hundreds of people throwing rocks in the capital Niamey today.
At least two police cars were burned in a second day of protests - with Agence France-Presse also reporting that churches were targeted.
Peaceful marches took place in the capital cities of Mali, Senegal, Mauritania and Algeria, all of which are also former French colonies in Africa.
One protester in Niger told Reuters news agency: "They offended our Prophet Mohammed, that's what we didn't like."
Three civilians and one police officer have been killed during an anti-French protest in Niger according to police sources, Reuters reports.
Rescuers found the bodies of 92 migrants, most of them women and children, strewn across the Sahara desert in northern Niger after their vehicles broke down and they died of thirst, authorities said.
Rescue workers said the bodies - 52 children, 33 women and 7 men from Niger were found near the Algerian border.
Many of the bodies were in an advanced state of decomposition, and some had been partly eaten by wild animals.
They were buried in a mass grave, close to where they died.
Authorities said 19 of the group reached Algeria by foot and were returned to Niger.
Two survived after walking the 50 mile trek back to Arlit, a mining down in Niger, and it was there that the alarm was raised.
Niger is ranked by the United Nations as the least developed country on earth. Every year thousands risk their lives by crossing through Northern Niger into North Africa and across the Mediterranean into Europe.
Most of those who make the perilous journey on ancient open-topped trucks are young African men in search of work.
Rescuers said the doomed convoy of women and children was puzzling.
The 92 bodies found in the Sahara desert were almost all women and children, an aid worker involved in an attempted rescue told the Guardian.
Almoustapha Alhacen who lives in Arlit, a mining down approximately 50 miles from where the bodies were found, was alerted after survivors reached the town on foot. He said:
A total of 92 bodies have been recovered in northern Niger after a truck carrying migrants broke down in the Sahara desert, the Associated Press reports citing a local official.
Dozens of migrants travelling in two vehicles have been found dead in the Sahara desert after running out of water, according to local officials.
About 40 migrants, many of them women and children, were found in northern Niger close to the border with Algeria, the mayor of Agadez said. Others put the numbers higher.
The route across the Sahara desert is used by many West Africans seeking a better life in Europe or the northern countries of Africa.
A rescue worker told BBC News that the bodies were scattered across a wide area around one of the vehicles, and that some of them had been partly eaten, probably by jackals.
One survivor told the Sahara FM radio station that they had been packed "like cattle" into overcrowded vehicles and were headed for Algeria.