A strong aftershock rattled southwestern Pakistan Saturday, as aid agencies warned that disease had begun to spread among tens of thousands of earthquake survivors waiting for relief supplies. The 5.0-magnitude quake struck just before 6am in the mountainous province of Baluchistan, where a powerful pre-dawn tremor on Wednesday killed up to 300 people and left 70,000 people homeless. There were no immediate reports of further casualties or damage as a result of the latest aftershock, the second strongest of more than 250 tremors to have shaken the region since Wednesday's quake. Aid has begun reaching devastated villages, but angry villagers in remote areas said they desperately needed shelter, with thousands of people whose mud-brick homes were flattened sleeping in the open in freezing temperatures. The UN Children's Fund said Friday they and Pakistani government officials assessed the situation in the worst-hit districts and were "concerned about the urgent needs of children and women". "With winter closing in, the most urgent needs of the survivors are shelter, safe drinking water, food, warm clothing and emergency medical assistance," a UNICEF statement said. Clean water was a "priority," it said, adding that children were especially vulnerable to diseases such as diarrhoea and cholera.