BEIRUT (Reuters) - Syrian President Bashar al-Assad has denied ordering his troops to kill peaceful demonstrators, telling the U.S. television channel ABC that only a "crazy" leader kills his own people. Assad is under growing international pressure, including a threat of sanctions from the Arab League, over a crackdown on nationwide anti-government protests in which the United Nations says more than 4,000 people have been killed. "We don't kill our people ... No government in the world kills its people, unless it's led by a crazy person," ABC's website on Wednesday quoted Assad as saying in a recorded interview. "Most of the people that have been killed are supporters of the government, not the vice versa," Assad said. Syrian activists say around a quarter of the more than 4,500 deaths they have recorded in nine months of protest have been among the security forces. Most foreign media have been excluded from Syria, making it hard to verify events independently. The Arab League has threatened to impose sanctions on Syria unless armed forces are verifiably withdrawn from towns and cities and a political dialogue is opened with opposition representatives. Major Western powers as well as neighbours Turkey and Jordan are calling on Assad to step down. U.S. Secretary of State Hillary Clinton said on Tuesday that Washington and its NATO allies wanted Assad to make way for a government ready to establish the rule of law and protect "the rights of all citizens, regardless of sect or ethnicity or gender". Syria's official news agency SANA said the army fought back gunmen who tried to block the Aleppo highway in the tense Hama district on Wednesday and killed one "terrorist". Experts defused seven improvised bombs in Hama district, it said. An army pilot was shot in front of his home, the agency said. An activist website said an army armoured personnel carrier was destroyed in clashes between troops and defectors near the radio station in the city of Saraqeb on the Hama-Aleppo highway. Heavy gunfire was reported in Hama city on Wednesday afternoon. On the tense border with Turkey, Syrian troops opened fire in sustained bursts on Wednesday, according to residents of Turkish villages. Peaceful protests against Assad , inspired by the Arab Spring in Tunisia and Egypt, were met with massive force as soon as they began in March. Now Syria is creeping closer to civil war as armed opposition groups organise and move into some city districts. Assad conceded that some members of his armed forces had gone too far, but said they had been punished. "Every 'brute reaction' was by an individual, not an institution, that's what you have to know," he told ABC's Barbara Walters. "There is a difference between having a policy to crack down and between having some mistakes committed by some officials," he said. "There was no command to kill or be brutal."