REBELS in Sierra Leone penetrated deep into UN-held territory late on Saturday to attack the town of Masiaka, 45km east of Freetown, before withdrawing, according to UN sources. The source said Unamsil troops sustained no casualties in the attack. The assault on Masiaka is the closest the rebel Revolutionary United Front has come to the capital since the British intervention force left midweek. The RUF has being making what military sources describe as probing attacks over the last week, including an assault on Thursday on Port Loko which lies 50km northeast of Freetown. These attacks have caused up to 100000 civilians to flee their homes causing what the World Food Programme has described as an humanitarian emergency.