One of ousted Libyan leader Moammar Gadhafi's surviving sons has had his phone cut off and been placed under house arrest in Niger after warning of a revolt against Libya's new government, authorities in Tripoli said Sunday. Saadi Gadhafi has been in Niger since September, following the collapse of his father's 42-year rule. He had been granted asylum, but Libyan authorities renewed demands for his arrest after he told the satellite news network Al Arabiya that "a new popular uprising" was brewing in his home country. Nigerien officials would not comment on the move. But Libya's National Transitional Council, which replaced the Gadhafi regime, said Saadi Gadhafi's comments "were considered a violation of the terms of his residency granted by Niger." "Saadi used the asylum he was granted in Niger on humanitarian basis to carry out acts of aggression against the Libyan people and their glorious revolution," NTC spokesman Mohammed Nasr al-Hraizi said in a government statement. Libya's new government complained to Niger about Saadi Gadhafi's interview, demanding Niger "take stringent measures, including his extradition to Libya." The move came as Libya prepares to mark the anniversary of the February 17 revolt that toppled the elder Gadhafi six months later. Few details have been announced, but commemorations are expected in Tripoli; in Benghazi, where the revolution began; and in Misrata, one of its major battlegrounds. Security has been tightened in Tripoli, with new checkpoints going up around the city in recent days. Gadhafi loyalists have been circulating text messages and YouTube videos talking about a new uprising around the anniversary date. Gen. Youssef Mangoush, the new chief of staff of the Libyan armed forces, said there has been no direct threat regarding the anniversary, but said the government would take all steps necessary to head off any new revolt. The transitional government in Tripoli is still working to build a new national army and police force. The NTC has set elections for a new National Assembly in June. But several revolutionary militias and regional factions have held onto their weapons and fought occasional clashes with each other, and ordinary Libyans say their biggest concern is security. Saadi Gadhafi was a prominent businessman and onetime head of Libya's national football league before his father's government fell to a six-month revolt in late August. The new Libyan government has accused him of misappropriating properties through force and armed intimidation, and the multinational police agency Interpol issued a "red notice" calling for his arrest in September. In his interview with Al Arabiya, he said he had been in touch with Libyans "on a daily basis" and said several groups were ready to take up arms against the new government. "I call everyone to be prepared for this uprising, and be ready for the zero hour," he said. "Because when it happens, it will a real uprising." He added that he could return to Libya and "stop those acts of revenge," and he urged armed factions in Libya "to meet and discuss and achieve real peace this time." The elder Gadhafi was killed by NTC fighters in October, along with his son Mutassim. Another son, Khamis, was reported killed in battle as the regime imploded in August. Gadhafi's second-eldest son and closest adviser, Saif al-Islam Gadhafi, is now awaiting trial in Libya. The elder Gadhafi's wife, three other children and several grandchildren have fled to neighboring Algeria.