By Joe Brock
MAIDUGURI (Reuters) - Nigeria claimed an early success for its military offensive against Islamist insurgents in the northeast on Monday, saying the militants' activities had been stifled by nearly a week of attacks on their bases.
Military officers in the combat zone, deep in a semi-desert frontier region, said operations continued and that troops faced considerable opposition from well-armed Boko Haram fighters.
A presidential spokesman issued a statement saying the biggest drive yet against the four-year-old rebellion had made progress since President Goodluck Jonathan declared a state of emergency in three troubled states last Tuesday.
"The insurgents have been dislodged from their previously safe havens and camps while many have been apprehended, and their activities in the affected states have been brought to a total halt," he said of operations around Lake Chad, along Nigeria's northeastern borders with Cameroon, Chad and Niger.
Thousands of additional troops have been deployed in the states of Borno, Yobe and Adamawa in an operation that has targeted areas of Africa's top energy producer where Boko Haram has established bases and weapons dumps. Warplanes were used to destroy some militant camps on Friday.
Jonathan has won support for decisive action, although many doubt whether Boko Haram, adept at going into hiding under pressure and then resurfacing, can be defeated militarily.
A record of human rights abuses by the Nigerian armed forces has seen Western powers voice concern about the offensive.
A military source in Maiduguri told Reuters the operation was facing major hurdles, as the Islamists were well armed and ready. Some had already gone into hiding, he said. Soldiers were conducting house-to-house raids, another military source said.
A spokesman for Nigeria's defense headquarters, Brigadier-General Chris Olukolade, said in a statement that several Boko Haram camps had been destroyed in areas such as New Marte and Hausari, which were now back under control of the government.
He added that 120 militants were detained at a funeral for one of their commanders killed by special forces. Others had fled towards the Chad and Niger borders, he said.
An all-day curfew imposed in the Borno state capital Maiduguri and other areas on Saturday was replaced by an order to keep indoors overnight, military spokesman Lieutenant Colonel Sagir Musa said. The blanket restrictions had raised fears of a humanitarian crisis if food supplies were unable to move around.
Traffic remained at a trickle in Maiduguri, as many frightened residents were shuttered in their homes. On one normally busy road, the only life was a boy riding a rusty bicycle past a soldier hunched behind a sandbag bunker.
On another street, women wrapped in veils shaded themselves from the midday sun underneath old trees, while their children threw stones against the crumbling walls of an abandoned market.
"I can't get my own produce to sell because the roads into town are blocked and even then who would I sell it to?" said fruit seller, Ibrahim, 28, who was afraid to give his surname, in front of a wooden cart stacked with oranges and watermelons.
"We want to be supportive but this offensive has already taken its toll and the longer it goes on the more people will lose patience and support for the soldiers," he said.
Boko Haram is fighting to carve an Islamic state out of Nigeria, a country of 170 million, around half of whom are Christians. Thousands have died in fighting since it launched an uprising against the government in 2009.
The brigade commander for Adamawa state, Brigadier-General Fatai Oladipo Ali, addressed a contingent of 200 soldiers, part of an expected 1,000 reinforcements being sent to the state.
"There will be no hiding place for terrorists," he told the troops on Monday. "The insurgents signed their own death warrants by taking up arms against the Nigerian state."
The United States, European Union and rights groups are concerned about long running military abuses against civilians.
Ali warned soldiers against "harassing innocent people".
President Jonathan pledged in Monday's statement that troops would follow "acceptable international rules of engagement" and "pay particular attention to the safety ... of citizens".
U.N. and Red Cross officials said some 1,500 people had fled Nigerian for Niger in the past two weeks and said they feared an increase in numbers.
(Additional reporting by Imma Ande in Yola, Abdoulaye Massalatchi in Niamey and Lanre Ola and Isaac Abrak in Maiduguri; Writing by Tim Cocks; Editing by Jon Hemming and Alastair Macdonald)