In Yemen, at least 17 people have been killed in a government assault on protesters in the capital Sanaa. Witnesses said the demonstrators came under attack in the capital's Change Square – the focus of the protests. The attack on the camp's southern end reportedly started late on Friday. Reports quoting a Yemeni pro-opposition officer also say that nearly 100 people were injured in the fighting.Other reports spoke of government troops shelling the 4 kilometres stretch of avenue which protesters have dubbed Change Square. Earlier on Friday, at least 13 people reportedly died in fighting in the capital.The violence comes after President Ali Abdullah Saleh returned from Saudi Arabia three months after surviving an assassination attempt. After his surprise return to Sanaa, President Saleh called for a ceasefire to stop violence which has already claimed about 100 lives this week, mainly of unarmed anti-government protesters. He was quoted by the state news agency Saba as saying he was carrying the dove of peace and an olive branch.