Whenever Emmanuel Ali Talka hears news of a female suicide bombing in Nigeria, he is paralyzed with fear despite having found relative safety in neighboring Cameroon.

Talka, a 36-year-old trader from Nigeria's Borno state, fled attacks by Boko Haram Islamists with his two wives and four of their children. In the chaos, though, his three daughters were separated from the family, last seen being dragged off by militants.

Now Talka fears Happy, aged seven, and Daga and Lakwa, both five, could be strapped up with explosives and dispatched as suicide bombers.

"I think of them all the time. I don't eat. I don't drink. I cannot sleep," Talka told Reuters at a refugee camp in Minawao, in north Cameroon, where rows of white tents now occupy fields where millet and coffee once grew.

"I don't know whether they are alive or not. They are very small and will not know what to do or defend themselves. I am dying inside," a fraught-looking Talka said, choking back tears.

Girls as young as 10 are known to have been used as suicide bombers by the Sunni jihadist group, which has waged a six-year campaign to carve out a caliphate in northern Nigeria and is now increasingly attacking neighboring states.

Nigerian forces have launched an offensive on the militants while neighbors Niger, Chad and Cameroon are seeking to hold the militants within Nigeria's borders ahead of a ground-and-air offensive by a regional task-force due to start from the end of next month.

But there is deep concern over the plight of those forced to abandon their homes by the waves of fighting and killings.

Aid workers estimate at least 1 million people in Nigeria have abandoned their homes. Another 157,000 have fled into neighboring countries, according to U.N. figures.

WAVES OF ATTACKS

Talka and his family fled their home in Ngoshe, a village in the Gwoza area that is the heartland of Boko Haram's insurgency, after waves of attacks by militants killed hundreds and forced 20,000 people to scatter into Cameroon in September.

They spent several weeks hiding in nearby hills.

Then, on Oct. 1, the area was again attacked by Boko Haram fighters. "They were shooting all over. We ran in different directions and I lost my family," Talka said.

Reunited with his wives and four of their seven children the next day, Talka crossed into Cameroon, where 32,000 Nigerians are crammed into the Minawao camp, initially built for 18,000.

Refugees lack toilets, water must be trucked in from afar and some have resorted to begging in nearby villages due to the shortage of food.

Minawao is full of tales of suffering and escape like Talka's.

Hassan Abba, a trader based in neighboring Benin, returned to his home in Ashigashiya, in Borno state, in December. He was on holiday and hoping to set up a business and get married.

These plans were torn up when Boko Haram militants stormed the town. "I ran into the bush, but my father and his brother were killed. They burned our house and everything I own."

Abba re-emerged to bury his father and uncle, before crossing into Cameroon, where he has been since January, sleeping in a hall with 46 other new arrivals.

Nigeria has delayed by six weeks a presidential election that had been due on Feb. 14, partly to allow the military to contain the insurgency in the northeast, where millions risked being disenfranchised due to violence.

Few believe that the six-year uprising can be seriously dented in six weeks.

But, for Abba and Talka in Minawao, reports of concerted action against the militant group are rekindling hopes of returning home to search for missing relatives.

"As soon as I hear Ngoshe is free, I'm going back," Talka said. "I have to find my daughters whatever it takes."