Bahrain has arrested a prominent human rights activist and critic of the country\'s ruling family. Police seized Nabeel Rajab, head of the Bahrain Centre for Human Rights, when he returned from Beirut on Saturday evening, Sayed Yousif Almuhafda, a member of the centre, said. He had met the representative of the UN High Commissioner for Human Rights on his visit to Lebanon. \"The police arrested him near the plane\'s door. They said they had an arrest warrant from the public prosecutions office,\" Mr Almuhafda said. \"We don\'t know what the new charges are yet,\" he said, adding that Rajab already faced earlier charges of calling for and taking part in unauthorised protests. In a statement, Bahrain\'s ministry of interior confirmed Rajab\'s arrest \"for committing a number of crimes punishable by law\". It gave no more details. Bahrain, which is ruled by a Sunni Muslim monarchy and hosts the US Fifth Fleet, has been in turmoil since activists, mainly from the majority Shia community, began protests for democratic reforms in February 2011 after successful popular revolts in Egypt and Tunisia. The authorities tried to crush the uprising with martial law and brought in Saudi troops. The ferocity of the crackdown stunned the Shia community and the unrest persists, with mass rallies by opposition parties and clashes between youths and riot police.