US President Barack Obama on Thursday extended by one year the national emergency order allowing sanctions against Libya to remain in place, the White House announced.
In a letter to congressional leaders, Obama said he was concerned by ongoing threats posed to US interests by the family of late Libyan strongman Muammar Gaddafi and members of his deposed regime.
"We are in the process of winding down the sanctions in response to the many positive developments in Libya, including the fall of Gaddafi and his government," Obama said.
"We are working closely with the new Libyan government and with the international community to effectively and appropriately ease restrictions on sanctioned entities," the US president said.
"However, the situation in Libya continues to pose an unusual and extraordinary threat to the national security and foreign policy of the United States."
Obama invoked "national emergency" regulations that authorise the president to impose sanctions on foreign countries.
"We need to protect against this threat and the diversion of assets or other abuse by certain members of Gaddafi's family and other former regime officials," he said.
On 16 December, the United States and the United Nations Security Council lifted most of the sanctions imposed on Libya under Gaddafi's rule. According to the US Treasury, more than $30 billion of Libyan assets were released.
The bloody uprising which began in February 2011 in Libya rapidly spread across the north African country and ended with the capture and killing of the ousted Gaddafi in his hometown in Sirte on 20 October.
Gaddafi had ruled the country with an iron fist for 42 years.
Last week, the US government imposed sanctions on a Libyan man accused of supporting one of Gaddafi's sons in his quest to return to power.
The Treasury Department said it was targeting Humayd Abd-al-Salam, 46, because he was acting for or on the behalf of Saadi Gaddafi.