JALALABAD (AFP) - Hundreds of Afghan villagers blocked a national highway Wednesday to protest the alleged killing of a father and son in a raid by NATO forces in the countrys east. NATOs International Security Assistance Force said the operation late Tuesday was in pursuit of a Taliban bomb-making expert linked to at least two attacks. But provincial police spokesman Abdul Ghafoor told AFP that two civilians had been killed when US-led coalition troops raided a house in Surkh Rod district, Nangahar province on Tuesday, and another three people detained. The coalition forces went into a house and killed a father and a son. They have arrested three people. They are innocent civilians, they are farmers and are not linked to any militant group, he said. Ghafoor said that police had contacted the interior minister and NATO to try to secure the release of those detained. ISAFs statement said the international force had come under fire as it approached a compound, and had killed insurgents. The operation had not killed or harmed any civilians, it said. As the security force approached the targeted compound... they immediately received enemy fire from multiple locations. The assault force decisively engaged and killed two of the enemy fighters and disarmed a third, it said. Up to 600 residents blocked the main highway in protest on Wednesday. , an AFP reporter on the scene said. They chanted Death to Americans and Death to Karzai, referring to Afghan President Hamid Karzai. The blocked section of highway connects Nangahar to the border of neighbouring Pakistan to the east, and to Kabul to the northwest. Civilian casualties are an incendiary issue in Afghanistan, often cited by President Hamid Karzai, who has repeatedly urged international forces to take preventative steps and to conduct operations jointly with Afghan troops.