* Residents allege abuse by army, army denies
* Military has deployed gunboats to search villages
* Militant group has claimed string of attacks on pipelines
By Tife Owolabi
OPOROZA, Nigeria, June 10 (Reuters) - The Nigerian army hasswept into villages in the southern swamplands in an operationto crush the Niger Delta Avengers group, but allegations byresidents of brutal tactics and rapes by some of its soldiersrisk stoking anger in the region.
The army has vowed to stop the militant group which hasclaimed a string of attacks on oil pipelines which have cutNigeria's oil output by half a million barrels a day to a20-year low. It denies the allegations of abuse.
The military has deployed dozens of gunboats in the Deltaswamps to search a cluster of villages that are home to a formermilitant leader whom officials link to the previously unknowngroup, residents said.
Community leaders and a security source said the sweep hasfailed to produce results, despite the arrest of some 15suspects, while relations with locals already angered by deeppoverty and oil spills have worsened.
"Our people are very angry with the arrest of innocentpeople in the name of looking for pipeline vandals," said EricOmare, a spokesman for Ijaw Youth Council, which represents themain ethnic group in the Delta region.
Five of the arrested were released after it turned out theywere oil workers unrelated to the militants. Activists sayseveral students who also had no connection to the Avengersremained in custody.
In interviews with Reuters, the first foreign news outlet tovisit the Oporoza community raided by the army, 10 villagerssaid soldiers had searched their houses in the middle of thenight after arriving in gunboats and surrounding the village.
Two villagers said they were raped, while two othersreported looting. One villager said he was struck by a soldierwith the butt of a gun.
"About 3 a.m., military men invaded our community. Four ofthem stormed my house and broke the doors," 50-year oldEbimobore Oboivu said, wailing in front of her hut in the creekscriss-crossed by oil pipelines.
"Two them raped me as the other two pointed guns at myhead," she said.
Army spokesman Rabe Abubakar denied troops had used force orraped anyone when searching Oporoza. "The reason we are there isbecause of some criminal guys who by all means decide to dounholy and inappropriate acts against their country," he said.
But the Delta state government, under whose jurisdiction thecommunity falls, has urged the military to launch aninvestigation. "This is not the first time such allegations aremade," state government spokesman Charles Anaigwu said.
A smashed window and bullet holes could be seen at one houseand one hut with an iron roof. A television set inside a househad a bullet hole from a gun fired by one of the soldiers, villagers said.
A second woman, Simply Timi, also described being the victimof a gang rape. "I heard a loud bang on my door with three armymen. One of them pinned me to the ground and they all raped me."
President Muhammadu Buhari has launched a reform of the armywhich has long faced accusations of abuses. But rights groupsroutinely accuse soldiers of detentions without arrest warrant,looting and beating of prisoners.
In April, the United States urged Nigeria to investigate areport by Amnesty International that soldiers killed hundreds ofShi'ite Muslims in the northern city of Zaria in December. Thearmy has said it acted in self-defence after the sect hadambushed a convoy.
CALLS FOR INQUIRIES
Oporoza, at the centre of a group of villages, is home toGovernment Ekpemupolo, known as Tompolo, a former militantleader who laid down arms with other commanders in 2009 under anamnesty promising generous cash payments.
Buhari, faced with a revenue squeeze due to low oil prices,has cut funding for the amnesty plan, causing widespreadresentment in the Delta, where the plan also funds job trainingfor the unemployed.
Officials link Tompolo with the attacks, saying they beganin January, around the same time that a court issued an arrestwarrant for him on graft charges, prompting him to go intohiding. Tompolo has denied any link to the Avengers.
Security officials say villagers have been hiding militantslike Tompolo.
Soldiers ransacked Tompolo's compound and searched dozens ofhuts but a Nigeria-based security source, asking not to benamed, said the army sweep had not generated any leads about whowas behind the militant group.
"You can't ruin the life of a whole community because of oneman," said Nelson Okagbami, an Oporoza community leader.
He said he saw soldiers dragging away one wounded teenager."Bullets were flying around. I had to hide in a church," hesaid.
At a meeting earlier this week, Delta state governors agreedwith Vice President Yemi Osinbajo to address local grievances.But in Oporoza people fear the army will come back.
"Soldiers pointed guns at me and I fell to my knees beggingbefore they left me alone," said Tari Maka, a food vendor inOporoza. "When will this end because we don't even understandwhat is happening?" (Writing by Ulf Laessing; Editing by Richard Balmforth)