Four Yemenis, including a policeman, were killed and 13 others wounded in two days of clashes between police and anti-government protesters in southern Yemen, medics and witnesses said. The deaths bring the toll of Yemenis killed since demonstrations broke out in the south in late April to sixteen, including five security force members. The Sanaa government has blamed the protests on southern separatists. A policeman and a demonstrator were killed Sunday in clashes in the village of Labouss, in the southern province of Lahij, while another demonstrator was wounded in similar confrontations in the neighbouring village of al-Eind, witnesses said. Protesters chanted slogans against the government, which is controlled by northerners, and carried posters of Ali Nasser Mohammed, the former president of South Yemen, which was united with North Yemen in 1990.