A Nigerian Islamist sect blamed for dozens of deadly bomb blasts and shootings has shown increasing signs of links to outside groups such as Al-Qaeda's north African branch, analysts say.
While there has been no clear proof of such ties, Western diplomats and security experts point to the growing sophistication of attacks by the sect known as Boko Haram as well as claims made on websites and elsewhere.
The possibility of such links have led to fears among Western countries, with Nigeria the largest oil producer in Africa, the continent's most populous nation and a major crude supplier to the United States.
"We are very concerned about the linkages between Boko Haram and other extremist organisations in Africa and other places," US General Carter Ham, commander of US Africa Command, told local journalists during a visit to Nigeria this week.
A Nigerian military spokesman said he believed Boko Haram had links with Al-Qaeda, pointing to the types of bombs used recently.
"With the presence of Al-Qaeda in nearby African countries like Mali, Niger and Algeria, it's very easy for Boko Haram to establish links with Al-Qaeda," said Lt Col Hassan Mohammed of a task force tracking the sect.
Some also name Somalia's Shebab rebels as having a possible connection based on statements from supposed sect members.
Other indications have come from at least one statement believed to be from Al-Qaeda in the Islamic Maghreb (AQIM) indicating some level of contact between the two groups. AQIM, Al-Qaeda's north Africa branch, has carried out kidnappings and attacks in nearby countries.
It is a controversial topic in Nigeria, with some pointing out that both Boko Haram and the country's security agencies may benefit by speaking of such links.
For the sect, it would give them more power, while Nigerian authorities could use such claims as an excuse for why they have been ineffective in stopping the group's near daily attacks, some analysts say.
The military task force tracking the sect has been accused of carrying out major abuses against civilians, including killing residents and burning their homes after alleging that they collaborated with the sect.
"For me, it is still a local insurgency," said Kyari Mohammed, a Nigerian history professor working on a book on Boko Haram. He said, however, the Islamists gained fresh bomb-making skills about a year ago, and even if a link does not exist, Boko Haram members surely draw inspiration from groups like Al-Qaeda.
A video obtained by AFP this month of a British man and an Italian kidnapped in northern Nigeria in May has added to the controversy. In the video, the captives say that their abductors are from Al-Qaeda, an assertion impossible to verify.
"Some high officials in the Nigerian government strongly believe Al-Qaeda is present," a Western diplomat said on condition of anonymity. "They just don't have proof of it."
As for Boko Haram, the diplomat said the government appeared to have no viable plan to stop it. It has formed a committee to look into whether to negotiate with the Islamists, but identifying whom to holds talks with could be problematic.
The sect has claimed to be fighting for the establishment of an Islamic state in Nigeria, whose 150 million population is roughly divided in half between Christians and Muslims.
Many say the sect appears to have various factions, but there is disagreement on details. There seems to be a core group of Islamists, but possibly another faction exploited by politicians to carry out attacks and others with varying interests, analysts say.
In any case, Nigeria's deeply rooted corruption and poverty provide fertile ground for such groups to take root, analysts say.
"It's a ripe environment of youth that are unemployed and frustrated," the diplomat said. "There is money to be made in northern Nigeria if you are coordinated enough and you know the right people to get in touch with."