KHARTOUM - Sudan arrested its former spy chief and other senior military and security officers on Thursday after foiling what officials said was a plot to incite chaos and target leaders in this oil-producing African state. Witnesses told Reuters they saw army tanks and armored vehicles moving down a main street in the tightly-controlled center of Khartoum around midnight, but the city appeared normal by the morning. Sudan's President Omar Hassan al-Bashir has kept up a near 25-year hold on power, even as a series of uprisings troubled the country's poor border areas, including the conflict-torn region of Darfur. But Sudan has been stuck in economic crisis since the south - the source of most of its known oil-reserves - declared independence last year under the terms of a peace deal. High prices for food and other basics have added to widespread public anger over losing the south and have emboldened opposition activists to call for protests. Analysts say the crisis has also exacerbated divisions in the government. Unrest over price rises and food and fuel shortages has preceded coups to overthrow the government in Sudan in the past. Salah Gosh, former head of Sudan's powerful intelligence and security agency, was arrested with others on suspicion of "inciting chaos", "targeting" some leaders and spreading rumors about Bashir's health, the information minister told reporters. "Thirteen people were arrested," the minister, Ahmed Belal Osman, said. "The situation is now totally stable." Witnesses said they saw military vehicles on a major street that runs alongside the city's airport overnight.