Nigeria's secret police have arrested and charged 45 suspects over an alleged Boko Haram plot to attack the country's financial hub, Lagos, sources with knowledge of the matter told AFP on Sunday.
"About 60 suspects were picked up from different locations in Lagos by the Department of State Services [DSS] acting on intelligence information they were planning to attack Dolphin Estate in Ikoyi last month," said one source.
Both sources, who asked not to be identified for security reasons, said some of the suspects were released after preliminary investigations, while 45 others were taken to a magistrate court on Friday.
"They were arraigned on holding charges. The DSS urged the court to remand them in prison pending further investigation and their eventual arraignment before a high court," said one.
Dolphin Estate is a gated community on the upscale Ikoyi island, which is home to wealthy Nigerians as well as expatriate workers, many of them in the oil and gas industry.
Any attack on Lagos, which drives Nigeria's economy and is seen by many foreign governments as a gateway to West Africa, would likely send shockwaves through both.
Lagos State Information Commissioner Steve Ayorinde on Saturday called for the public's help in ensuring the safety of the megacity's 20 million-strong population.
"Our appeal goes to every school, housing estates, religious houses, markets and shopping complexes, hotels and restaurants and sporting arenas to take issues of security and personal safety more seriously these days and to work with both the government and security agencies in promptly reporting any persons with suspicious activities or unusual gatherings that may compromise security," he said.
"Care must also be taken in how domestic servants and house aides are also employed," he added in a statement.
Boko Haram, which wants to carve out a hardline Islamic state in Nigeria's northeast, has threatened to move south to spread its six-year-old insurgency in the country.
The capital, Abuja, has been hit several times, most recently on October 2 when three suicide bombers killed 18 in two satellite towns - while Lagos was attacked last June.
The car bombing, near fuel depots and the city's main port, killed at least four and although denied by the authorities, was claimed by the group's shadowy leader, Abubakar Shekau.
In one propaganda video, Shekau threatened to hit Nigeria's oil-producing south.
Security analysts said at the time the Lagos bombing was likely to have been carried out by a small group of Boko Haram sympathisers, with no direct link to the group's high command.
President Muhammadu Buhari, who came to power in May on a promise of crushing Boko Haram, has given his military commanders until the end of the year to bring the insurgency to a close.
That has led to a slew of announcements, particularly from the military, about progress in the counter-insurgency.
But at the same time suicide attacks and bombings against "soft" civilian targets have continued. Nearly 170 people have been killed this month and more than 1 420 since Buhari came to power, according to an AFP tally.
At least 58 people were killed on Friday in blasts at two mosques in the Borno state capital, Maiduguri, and the capital of neighbouring Adamawa state, Yola.