KUNDUZ (AFP/Reuters) - Nato aircraft opened fire on hijacked fuel trucks in northern Afghanistan before dawn on Friday, killing as many as 90 people - a mix of Taliban and civilians, - in an incident that could trigger a backlash against Western troops and sparking new outcry over civilian casualties in the military raids. The Alliance initially said it believed the casualties were all Taliban fighters in the air raid in Kunduz province, but later acknowledged that large numbers of civilians were being treated in hospitals in the area. Officials claimed the dead were mostly insurgents, but Afghan President Hamid Karzai said any targeting of civilians was unacceptable. His office gave a death toll of 90 and said an investigation team had gone to the scene. It said he was deeply saddened and had sent investigators. Police and the Interior Ministry said up to 56 Taliban were killed and 10 more wounded, including a 12-year-old child, when a Nato air raid targeted the tankers after they were hijacked en route from Tajikistan to Kabul. Local Afghan officials were quoted as saying in some news reports that nearly half the people killed in the air raid were civilians who rushed the fuel trucks. Mahbubullah Sayedi, a spokesman for the government in the increasingly unstable Kunduz province, gave the highest death toll, saying 90 people were killed. Most of them are Taliban. It was an Isaf (International Security Assistance Force) airstrike. A small number of the casualties are local civilians, including a few children who had come to take free fuel, he said. Provincial Governor Mohammad Omar said he believed half of those killed were militants, while provincial police chief Abdul Razzaq Yaqubi said 55 of the 90 dead were fighters. Isaf spokesman Brig-Gen Eric Tremblay later said: Based on the information we are receiving from Kunduz, it would appear that many civilian causalities are being evacuated and treated in the local hospitals. The Thursday night bombing saw Nato , the US and Afghanistan launch investigations, and revived controversy over civilian casualties in Western military operations, a major source of tension with the government. Shoes, an AK-47 rifle, swatches of burned clothing, the carcass of a donkey with a woven saddle cloth and yellow plastic jerry cans lay scattered across the pebbled banks of the river next to two incinerated fuel trucks. In nearby Yaqubi village, hundreds of mourners buried 18 bodies, some of which were burnt so badly the faces were unrecognisable, an AFP reporter said. Wounded people with extensive burns crowded a hospital in Kunduz, where witness Mohammad Daud, 32, said villagers rushed to one of the trucks when it got stuck in the river to take free fuel at the Talibans invitation. Everyone around the fuel tanker died. Nobody was in one piece. Hands, legs and body parts were scattered everywhere. Those who were away from the fuel tanker were badly burnt, he told AFP. An AFP reporter said around eight were in terrible condition - the skin burnt black and peeling off to expose raw red muscle. Others were silent in agony with incinerated clothes stuck to their flesh. Expressing concern at the scale of civilian casualties in Kunduz, European governments warned that the airstrike risked undermining the alliances mission, as they endorsed a swift inquiry into the bombing. Its vital that Nato and the Afghanistan people come together to resolve the countrys problems, British Foreign Minister David Miliband told reporters in Stockholm ahead of a meeting of EU foreign ministers. And obviously incidents like this undermine that, he added. Thats why its important that we are open and clear about what happened and make sure it does not happen again. Nato Secretary-General Anders Fogh Rasmussen pledged to conduct a thorough investigation. Certainly, a number of Taliban were killed, Rasmussen said. There is also the possibility of civilian casualties as well, but it is not yet clear. The UN mission in Afghanistan dispatched its own investigation, expressing concern about reports of civilian casualties and calling for the casualties to be properly cared for. Isaf said it bombed two stolen fuel trucks spotted on the banks of the Kunduz river, saying a large number of insurgents were killed but expressing regret for any unnecessary loss of human life. A Taliban spokesman, Zabihullah Mujahid, said fighters had captured the two fuel tankers. One had become stuck in mud by a village, and the fighters went to try to tow it when residents gathered to take the fuel and the crowd was struck. Meanwhile, a suicide car bomb attack ripped through an Afghan security company vehicle on Friday in Del Aram district of Farhar, killing three local guards, including the commander of the security company, providing an escort to Western troops in Afghanistan, police said. Another suicide attacker targeted namazis leaving a mosque in Herat, wounding eight people, said Noor Khan Nikzad, police spokesman for Herat province. Meanwhile, a French soldier was killed and nine others wounded when a booby trap exploded against their armoured personnel carrier as they carried out reconnaissance in the Showki region north of Kabul Afghanistan, officials said Friday.