* Boko Haram reportedly chased army out of Damboa two weeks ago
* 15,000 civilians fled after weekend attack
* Jonathan meets parents of abducted girls
By Lanre Ola
MAIDUGURI, July 22 (Reuters) - An attack on a Nigerian army base in the northeastern town of Damboa and a massacres against civilians in surrounding villages over the weekend have left Boko Haram in effective control of a swath of territory, witnesses and security sources said.
While the insurgents have yet to establish bases in the small garrison town and nearby villages, a power vacuum has existed since Nigerian troops stationed there were pushed out two weeks ago. Raids on Damboa and six surrounding villages on the weekend also drove out 15,000 civilians, leaving the area largely in the hands of the Islamists.
That might represent Boko Haram's biggest strategic success since a military offensive dislodged it from several cities and towns in Borno last year. Witnesses said the militants had set up road blocks and hoisted their black al-Qaeda inspired flags in some places around Damboa.
"Boko Haram have actually taken over our communities," said Andrew Tada, a resident of Attagara village, one of those that emptied out after the weekend attack. "Boko Haram have sacked them and nobody dares go back."
He said that residents had fled to the mountains during the attack. When they returned, the militants had gone but the town was deserted. Boko Haram fighters then set up road blocks.
Boko Haram, which is fighting to carve an Islamic state out of Nigeria, has ceaselessly targeted civilians this year.
A soldier posted to the Damboa road said a military offensive was underway to clear the Islamists out, but there had been no security forces in the Damboa area for two weeks.
The five-year-old insurgency, which has killed thousands, has been in the international spotlight since Boko Haram fighters kidnapped more than 200 girls from a school in the northeastern village of Chibok in April.
An international and local campaign has heaped pressure on President Goodluck Jonathan to rescue the girls and do more to protect civilians in the remote northeast.
On Tuesday, 184 parents of the girls and 57 other girls who had escaped the rebels met Jonathan in the presidential villa - his first meeting since the kidnapping. They looked sad and distraught before and after the meeting.
"Our commitment is not just to get the girls out, it is also to rout Boko Haram completely from Nigeria. But we are very mindful of the safety of the girls," Jonathan told them, according to a statement after the meeting.
"We want to return them all alive to their parents. If they are killed in any rescue effort, then we have achieved nothing."
A parent at the meeting, Ayuba Alamison, who has two daughters with the rebels, said Jonathan had promised they would be brought home soon.
Defence spokesman Major-General Chris Olukolade appeared to deny that Boko Haram had taken over Damboa and the surrounding areas on Monday, saying "our patrols are active and they are stepping up their activities to reverse any insecurity there."
But residents of Damboa fear a total takeover.
"If they can attacked the military the way they did and then come after us, it means they are on the ground in the town and nowhere is safe," said Mohammadu Birma, who fled on Friday.
Security sources say Boko Haram are effectively pursuing a scorched earth policy, driving out authorities and anyone else who does not support their effort to create a de facto Islamic state. (Additional reporting by Tim Cocks in Lagos and Felix Onuah in Abuja; Writing by Tim Cocks; Editing by Larry King)