By Tom Perry and Sylvia Westall BEIRUT (Reuters) - Islamic State fighters launched simultaneous attacks against the Syrian government forces and Kurdish militia, moving back onto the offensive after losing ground in recent days to Kurdish-led forces near the capital of their "caliphate". After losses to the Kurds backed by U.S.-led air strikes, Islamic State sought to retake the initiative with incursions into the Kurdish-held town of Kobani at the Turkish border and government-held areas of Hasaka city in the northeast. In a separate offensive in the multi-sided Syrian civil war an alliance of rebels in the south of the country also launched an attack with the aim of driving government forces from the city of Deraa.