The disaster agency is preparing aeroplanes and helicopters to carry out water-bombing of the fires," he said.
More than 25,000 people have fallen ill in recent days due to high air pollution, with most suffering respiratory tract infections, said Riau disaster chief Said Saqlul Amri.
The emergency status means health centres must see patients free of charge, he said.
Local media reported that some flights to Riau had been cancelled this week while others were diverted, and schools were closed in some parts of the province.
Last year's fires strained ties between Indonesia and its neighbours, prompting an apology from Indonesian President Susilo Bambang Yudhoyono to Malaysia and Singapore at the height of the crisis.
Indonesia is the world's biggest producer of palm oil -- which is found in everyday grocery items, such as shampoo and shaving gel -- and Riau is the country's main palm oil hub.