Security forces in the central Nigerian city of Jos seized a truck laden with bomb-making equipment on Friday, less than three months after explosions tore through Christmas Eve celebrations.
Sectarian violence in the region, where the mostly Muslim north meets the largely Christian south, has killed at least 200 people since the December attacks and the security forces are on high alert ahead of national elections next month.
Charles Ekeocha, spokesman for a joint military and police taskforce, said the truck was carrying a large amount of ammonium nitrate, a fertilizer which can be used to make improvised explosive devices, as well as fuses and detonators.
"The vehicle was intercepted at our checkpoint coming from (the northern city of) Kaduna to Jos very late in the night," Ekeocha told reporters.
The tensions around Jos are rooted in decades of resentment between indigenous groups, mostly Christian or animist, and settlers from the Muslim north who are vying with them for control of fertile farmland and economic and political power.
Plateau state, of which Jos is the capital, is seen as a potential flashpoint, a few weeks before presidential, parliamentary and state governorship elections.
Previous polls in Africa's most populous nation have been marred by local violence but the use of bombs and other explosives is a new development.
Three people were killed and 21 injured by an explosive device thrown from a car at a ruling party election rally in the town of Suleja near the capital Abuja last week.
There have also been fire bomb attacks on opposition party offices and campaign rallies in Bayelsa state in the southern oil-producing Niger Delta.
The ruling party candidate has won every presidential race since the end of military rule 12 years ago and President Goodluck Jonathan, the first head of state from the Niger Delta, is widely considered the front-runner.
But he is resented in parts of the north because, if he wins, he will be serving what would have been the second term of late President Umaru Yar'Adua, a northerner who died last year.
The parliamentary and state governorship elections are also expected to be closely fought, and the ruling People's Democratic Party's (PDP) strong parliamentary majority and regional dominance are expected to weaken.
