New flood warnings have been issued in Pakistan as the swollen river Indus carries recent heavy rains towards south through the country. Tens of thousands of people are fleeing their homes in response. Officials say that a series of towns in north-west Sindh close to the border with Balochistan have been placed on high alert. Some river defences have been breached while others are under threat. The latest warnings have added to the continuing crises in Pakistan as it struggles to cope with the worst flooding in its history., The authorities say as many as 20 million people have been affected. The United Nations says 6 million people desperately need emergency aid but most still have not received it. Reports from Pakistan say that Islamabad has received new pledges of aid totaling more than three hundred million dollars to deal with disastrous floods. But the UN says, millions of flood victims have not received any aid.