GENEVA (Reuters) - Sanctions could persuade Libya's ruling elite to ditch Muammar Gaddafi, a senior US official said as US Secretary of State Hillary Clinton on Monday sought to stiffen the world's response to Libya's uprising. Clinton was in Geneva to meet foreign ministers from key European countries as well as Arab and African allies, and was scheduled to urge a more robust response on Libya to the UN Human Rights Council later in the day. US officials say UN and US sanctions on Gaddafi and his core supporters may "peel off" the Libyan strongman's remaining allies and seal his political fate. "We need to deploy the tools that we have available to us right now to try to send a message not only to Gaddafi ... but to the people around Gaddafi, who are the ones we're really seeking to influence," the US official said on condition of anonymity. "Some of whom may in fact be rational. Some of whom may be interested in self preservation," the official added. World leaders have repeatedly denounced Gaddafi's use of force against civilians and urged him to quit but have been slow to take concrete action against his government almost two weeks after the uprising began. The UN Security Council voted on Saturday for an arms embargo and other sanctions targeted at Gaddafi and his inner circle, and referred the crackdown which has cost hundreds of lives to the International Criminal Court (ICC) in the Hague. Meanwhile, sons of Libyan leader Muammar Gaddafi have failed to persuade prominent Saudi clerics to issue religious rulings against a revolt that is threatening to bring down the veteran leader, Al Arabiya television said on Monday. The Saudi-owned channel said on its website that Gaddafi's son Saif al-Islam had contacted one cleric, Salman al-Awda, and Saadi Gaddafi had reached out to a second, Ayedh al-Garni, but both rejected their calls. "You are killing the Libyan people. Turn to God because you are wronging them. Protect Libyan blood, you are killing old people and children. Fear God," Garni said he told Saadi. Meanwhile, naval ships from China and South Korea are sailing to Libya to evacuate their nationals, Egyptian maritime officials said on Monday after the vessels entered the Suez Canal. An Indian naval vessel is also expected to pass through the canal within days en route to Libya, the officials said. Governments around the world have been scrambling to send planes. Meanwhile, France will send two planeloads of medical aid to the Libyan city of Benghazi, held by opponents of Muammar Gaddafi, marking the start of a humanitarian operation, Prime Minister Francois Fillon said on Monday. Fillon linked the aid mission to a wider effort by the French government to prevent an influx of immigrants from Libya across the Mediterranean, in the wake of an uprising that has shaken but not broken the rule of Muammar Gaddafi. France and Italy have both expressed concern that a collapse of organized government in Libya could lead Libyans and migrant workers there to flee to the southern shores of the European Union. "In a few hours two airplanes will leave for Benghazi at the request of the French government with doctors, nurses, medical equipment, and it will mark the start of a massive humanitarian aid operation for the people in the liberated territories," Fillon said in an interview on RTL. Opponents of the Libyan leader have taken control of Benghazi, the country's second city, and leading citizens have set up committees to act as a local authority and run services. Since the uprising against Gaddafi's rule erupted on Feb. 17, he has lost control of the east of the country, where Benghazi is located, and of several other major towns, though his loyalists still control the capital, Tripoli.