SOUTH AFRICA— Sappi and Mitsubishi Paper have each  announced increases across their portfolios for September. Another wave of paper price rises look set to impact the sector as two manufacturers announce further double-digit increases. Both mills said continuing rising cost and volatility in raw materials, energy and transportation. Sappi is to raise the prices of its its woodfree coated and uncoated papers, and paperboard by 8-10% from 12 September.“The cost outlook remains uncertain and Sappi will continue to adjust pricing if costs escalate further.” Mitsubishi HiTec Paper is set to raise prices across its entire portfolio by up to 15% for worldwide deliveries from 1 September. More paper mills are expected to announce price increases before the end of this month.