A large shipment of weapons has been seized by Nigeria's State Security Service at the port in Lagos city. The secret police say they intercepted 13 containers some of which had rocket launchers and grenades and other explosives hidden in the floorboards. An SSS spokeswoman told the BBC she could not say who owned the containers or their intended destination. But correspondents say the discovery has increased fears of possible violence during next year's elections. The ship's manifest said it was carrying building materials. So far only one container has been searched. "We have made some arrests, but for now the number and names cannot be disclosed," SSS spokeswoman Marilyn Ogar told the BBC. The BBC's Chris Ewokor in the capital Abuja says security agencies say there have increased surveillance at Lagos port following the bombings on 1 October during celebrations of the 50th anniversary of independence. In the past politicians have armed young men to use as their private armies and to rig elections. Oil militants in the Niger Delta - many of whom have disarmed - were originally armed in this way. A militant group which did not sign an agreement with the government in 2009 to end years of unrest in the oil-producing Niger Delta region is believed to be behind the independence day blasts. Source: BBC