Buses full of displaced people from the Diffa region of Niger fleeing fighting between army and Boko Haram on the border between Niger and Nigeria are checked by police on the outskirts of Zinder pictured on February 13, 2014
Zinder (Niger) (AFP) - Aboubacar, usually a worker for a non-governmental organisation, has now taken on another, more ominous role: watching out for suicide bombers.
"We watch everyone," he said in Niger's second-largest city of Zinder. "Last Thursday, a man in a turban whom we had never seen before came to the mosque. We asked him to leave."
His fears reflect the shifting threat of Islamist extremist group Boko Haram, which has in recent weeks carried out attacks across the border from its base in northeastern Nigeria as regional forces pursue them.
In the southern city of Zinder, the hot, dusty streets have seen a trail of refugees from Niger's Diffa, about 400 kilometres (250 miles) to the east.
Since February 6, Boko Haram has launched five bloody attacks in Diffa border territory. Zinder has so far been spared, but residents and local officials fear the violence could further spread.
The attacks have come as Niger moved to deploy troops to join a burgeoning regional campaign against the jihadists, who have taken control of swathes of northeastern Nigeria at a cost of more than 13,000 lives since 2009.
While the regional response has led to the beginnings of a fight back, it has also introduced new risks.
A recent air strike killed at least 36 mourners and wounded 27 others at a funeral in Abadan village straddling the border with Nigeria.
Some blamed the attack on Niger's own military, which declared that the aircraft's "origins remain undetermined". A local elected leader said that the Nigerian army was suspected, but Nigeria's air force denied all responsibility.
- Systematic searches -
North of the Nigerian frontier, Zinder is on high alert. At a main entrance to the town of some 350,000 inhabitants, teams of police officers take turns all day long to inspect vehicles under a blazing sun.
Cars, lorries, buses laden with luggage piled on top, minibuses and motorbikes are all systematically searched at a checkpoint marked by a simple rope stretched across the tarred road.
When a boy was hauled roughly out of a minibus, tension soared. People shoved each other and shouted, since Boko Haram is known for using youngsters in its attacks. But a nervous policeman said that the youth had merely been party to a scuffle.
The governor of the Zinder region, Kalla Moutari, says that rigorous inspections are vital and have already enabled the security forces "to intercept people who infiltrated the displaced population".
"A few dozen" people suspected of having ties with Boko Haram have been arrested around the town, which has for centuries been a major trading hub on a trans-Saharan route.
The suspects, all Niger nationals, have been transferred to the anti-terrorist unit in the capital Niamey, where the authorities on Tuesday organised a major protest march against Boko Haram.
The Nigerian extremists "have enlisted many of our young people" in southern Niger, the governor said in the vast reception room of his residence, stressing that "we can't minimise the threat".
Concern is all the greater since even before Boko Haram struck in Niger, security forces dismantled several "sleeper cells" of Islamist activists, Moutari added.
- 'No money, no clothes, no food' -
One man was recently arrested when found in possession of a book "that gave justifications for terrorism", a member of the security services said.
Aboard the buses that arrive in Zinder, "it's often the travellers who denounce the suspects," he added.
Beyond the security threat, the International Rescue Committee recently warned that thousands of people fleeing attacks in Niger's Diffa region and arriving in Zinder were in desperate need of food and supplies.
However, the governor said that of "almost 10,000 people" who came to Zinder, the bulk moved on towards the capital Niamey and other towns.
Zoulaha, Safia and Zeynabou, three young women from the same family who made their way from Diffa with a cluster of children, said they plan to leave Zinder despite their lack of means.
After an exhausting journey, they huddled at the Zinder bus terminal with their bags on the ground. "We have nothing, no money, no clothes, no food," Zeynabou said as she cradled a baby in her arms.
The trio was seeking a means to pay their way to Madaoua, their native village further west.
"When the war is over, we shall go back to Diffa," Zeynabou said.