Yemen's defence minister has escaped an attack on his convoy in the southern city of Aden, officials say. They said a car bomb exploded near Mohamed Nasser Ali's convoy, injuring several soldiers. Other reports said grenades were thrown. There has been a surge in violence in Yemen as supporters and opponents of President Ali Abdullah Saleh battle each other in the capital, Sanaa. Mr Saleh, who survived an attack in June, returned to Yemen on Friday. Details of Tuesday's attack in Aden are still emerging. One report said a car packed with explosives had been detonated by remote control. Another said the car was driven by a suicide bomber. It was not immediately clear who carried out the attack. In southern Yemen, security forces have been battling al-Qaeda militants who have taken advantage of the country's political instability.