Nigeria on Friday urged delegates due for the World Economic Forum (WEF) in Abjua next week "not to let terror win" by staying away after a second bombing in the capital in less than three weeks.

A suspected car bomb killed 19 people and wounded 34 on Thursday night in the suburb of Nyanya, about 8 km (five miles) from Abuja city center and next to the bush station where a rush hour bomb attack killed 75 people on April 14.

The bombs, along with the abduction of 200 girls from a secondary school in the northeastern village of Chibok near the Cameroon border, threaten to overshadow the WEF conference's emphasis on Africa's positive growth story.

The girls, who were taking exams, were taken away on trucks on the same day as the bus station bombing. Both attacks showed the powerlessness of Nigerian security forces to protect civilians against the militant Islamist group Boko Haram.

President Goodluck Jonathan's government will mount a huge security operation to protect the WEF scheduled for next Wednesday and Thursday.

A regional replica of the Davos, Switzerland, event, it will bring together international leaders, policy-makers, entrepreneurs and philanthropists.

"We want to state categorically that the President Goodluck Ebele Jonathan administration will not be diverted nor will it give in to these nefarious acts of terrorism," Finance Minister Ngozi Okonjo-Iweala said in a statement on Friday.

"The government has taken the strongest measures to ensure a safe forum. We ask participants not to let terror win."

Despite the repeated assurances on security, there were signs not all delegates were convinced that Nigerian authorities could keep the capital safe during the event.

Fernando de Sousa, General Manager of Microsoft Africa Initiatives, canceled his trip "for security reasons following the bombings in Abuja", a PR company representing the firm said.

The Islamists, who want to install a medieval Islamic kingdom in Nigeria, claimed the previous bombing and authorities blame them for the second one and the abductions.

NO SIGN OF GIRLS

Interior Minister Abba Moro told Reuters that security in Abuja city center would make it very difficult for any insurgents to find their way in.

He also said security forces were close to rescuing the missing girls.

"Defense high command is doing everything to secure the release of these girls. We are closing in on their location. Hopefully in the next couple of days, they will be rescued," Moro said in a telephone interview.

But he added: "The government has to be careful. Any all-out forceful rescue of these kids could undermine their safety."

He said efforts had been made seek out possible intermediaries for negotiation to get back the girls but declined to give any details of actual talks.

The United States said on Thursday it had offered to help Nigeria in its search for the schoolgirls. Britain has also offered support.

But parents of the missing pupils have started to despair of ever being reunited with them and they tend to disbelieve government claims that they are searching hard for them.

"We haven't seen any soldier or security personnel going into the bush in search of the girls, so we really don't understand where they are carrying out their search operation," Malam Maina, one of the parents, told Reuters.

About 250 parents protested in the village on Thursday to demand swifter action. Dozens of people protested outside Abuja's parliament on Wednesday.

A Borno state senator, Ahmed Zannah, fears the girls have been taken as "wives" by Boko Haram commanders - a grim echo of Uganda's Lord's Resistance Army, which abducted thousands of girls from central Africa for the same purpose. There has been no news of their fate beyond the roughly 50 who escaped.