BENGHAZI, Libya (AFP) - Almost 7,000 SAM-7 anti-aircraft missiles from ousted Libyan strongman Muammer Gaddafis arsenal have gone missing, a military official of the countrys new leadership said on Saturday. Gaddafis Libya bought about 20,000 SAM-7 missiles, Soviet- or Bulgarian-manufactured, General Mohammed Adia, in charge of armaments at the defence ministry, said at a symbolic ceremony to disable some of the stockpile. More than 14,000 of these missiles were used, destroyed or are now out of commission. Most of them were stockpiled in Zintan, southwest Libya, he said. About 5,000 of the SAM-7s are still missing ... Unfortunately, some of these missiles could have fallen into the wrong hands ... abroad, the general told reporters at a former arms depot of Gaddafis forces in Benghazi. He said Libyas National Transitional Council had found around 500 of the portable missiles. The guidance and firing systems of 10 of the SAM-7s were neutralised with the use of hammers in front of journalists, raising to 170 the number of missiles destroyed to date, said Adia. The United States has said it is working closely with Libyas new interim leaders to secure all arms stockpiles, amid concerns over weapons proliferation. The proliferation of arms raided from Gaddafis vast stores has been raising fears for Libyas future stability and that they could fall into the hands of radical groups like Al-Qaeda. A rocket killed two children Saturday as their family joined the quickening exodus of civilians during a two-day window to flee the battle for Muammer Gaddafis hometown of Sirte, a Libyan medic said. Some of the hundreds of people escaping the city said there had been civilian casualties there when residential buildings were hit, either by artillery fire from besieging new regime forces or by NATO air strikes. National Transitional Council (NTC) forces besieged the Ouagadougou Conference Centre on Saturday, a show piece venue in Sirte where Gaddafi hosted the launch of the African Union. A large force of some 100 vehicles, including anti-tank guns and multiple missile launchers, entered the city from the south at around midday (1000 GMT) and surrounded the compound. We are surrounding the Ouagadougou Centre, fighter Osama Blao told AFP as he returned from the front line. Several NTC fighters said the Red Crescent had asked them to stop firing because Red Cross officials were inspecting a hospital close to the centre. Some of the fighters pulled back after two hours of intense clashes, during which loyalist forces used snipers and mortar fire. The coast road west to Libyas third-largest city of Misrata was clogged with convoys of fleeing civilians, an AFP correspondent reported. The two children killed were torn to pieces, said Ahmed Abu AUD, a field medic on the western side of Sirte. They collected the body parts in bags. NTC chief Mustafa Abdel Jalil said that civilians were being given a chance to leave Sirte. A chance of two days has been given by the revolutionaries near Sirte so that civilians can leave the city ... It started yesterday (Friday), he told a news conference in Benghazi. However, Abdel Jalil gave no indication that this was in any way an ultimatum or that a major assault would follow the end of that period. Abdel Jalil claimed the battles for Sirte and the other remaining stronghold of Gaddafi support, the desert town of Bani Walid, were going well. The battles for Sirte and Bani Walid are going very well and they are currently fighting on the basis of an organised plan between the two areas, the NTC leader said. Among those fleeing, Redwan Abdulrahim, whose small truck was piled high with suitcases and other possessions, said the situation in Sirte was increasingly difficult. It was really bad. We didnt know where the bullets and rockets were coming from, he said. Hassan Duha, a commander in the Misrata military council operations room, said a growing number of Gaddafi troops were trying to hide among the escaping civilians. They throw away their IDs and they try to come out with the families, he said. An AFP correspondent saw one Gaddafi officer surrendering on Saturday. Major Mohammed Usba Hanish told his NTC captors that although he came from Gaddafis birthplace in the small town of Qasr Abu Hadi, 20 kilometres (12 miles) south of Sirte, he had not been fighting as he was on sick leave. I am not involved. If I was involved, I would not be here, he said. Hanish said that troops still loyal to the toppled dictator were facing growing shortages. The Gaddafi people are eating just bread. They are running out of food and ammunition. At midday (1000 GMT), NTC forces opened an artillery barrage from the east on administrative buildings in the city centre. We are targeting buildings where Gaddafis men are holed up. Our scouting teams have informed us that a lot of mercenaries are still in there and we are striking them too, said Colonel Hussein Idris as he supervised the barrage. An AFP correspondent saw young NTC fighters open up with six Russian-built 130 mm cannons in the desert, firing dozens of shells in an hour. Dozens of Pakistani migrant workers were among the hundreds of Sirte residents fleeing to the east. NATO struck one big building, Imarat Tamim, two days ago, with 12 or 13 bombs, said Ashiq Hussein, who fled the city with 11 family members, including six children. The whole building with nearly 600 flats is razed to the ground now. Hussein, an electrician originally from Lahore, worked in construction with a Libyan builder and has been in Sirte for 30 years. Two of my neighbours died yesterday in a NATO bomb which hit their home, he said as his family fled in two cars packed with essentials including mattresses, bags of rice and clothing. Asked why NATO was hitting civilian buildings, Hussein said: Maybe they have information that on rooftops there were Gaddafi men... But a lot of civilian buildings were getting hit. Also the incoming shells from NTC forces were hitting civilian homes. They are missing their targets and often hit civilian homes.