An Israeli court sentenced Jewish convert Asaf Ben-David to seven years in prison Tuesday for collaborating with a Palestinian militant _ his brother. Ben-David, a naturalized Israeli citizen who was born Hussam Sawafta in the West Bank town of Tubas, was found guilty earlier this month of assisting an enemy during wartime and of contact with a foreign agent. In their ruling, three judges of the Haifa district court noted that these are two of the most serious crimes on Israel's law books. The enemy agent Ben-David contacted was his brother, a Palestinian operative from Islamic Jihad. Ben-David was convicted earlier this month of helping his brother plan a bombing attack against Israelis. Ben-David left his home in the West Bank town of Tubas in the early 1990s, working as a laborer in Israel and later converting to Judaism, living for a time as an Orthodox Jew. He married an Israeli woman with whom he had four children and became an Israeli citizen. Ben-David re-established contact with his family in 2006, and agreed to help his brother, Salah Sawafta, obtain a large amount of nitric acid - a chemical which can be used to manufacture bombs - according to the court documents.