“Total coal exports to China rose from 3.3 million tonnes in 2008 to a substantial 49.3 million tonnes in 2009, rising from 1.3 per cent of total exports to 18 per cent in 2009,” the bank said in a commodities report.

Looking at Chinese customs data, Macquarie said China’s total coal imports in 2009 were up 208% year-on-year to 125.83Mt.

The investment bank said China was a net coal exporter of 17.43Mt in 2008, swinging to a net coal importer of 67.57Mt in 2009.

While there were fears China’s coal imports would fall off after mid-2009 with returning domestic production, Macquarie said the country’s coal imports had again accelerated in recent months and were up almost 30% in December compared to November.

“The key for the level of 2010 exports will be the strength of the recovery in demand from other parts of the world where Australian coal suppliers have long-term volume contracts,” the bank said.

“The diversion of material to China was opportunistic, as it coincided with temporarily reduced demand from non-Chinese buyers (especially in metallurgical coal).

“The ability of Australian suppliers to ramp up exports further appears to be limited by capacity constraints; thus, lower exports to China appear inevitable.

“This will keep the upward pressure on spot prices to the Chinese market as long as Chinese demand remains strong and domestic Chinese supply growth remains constrained.”

Looking at port data, Macquarie said Australia’s total metallurgical coal exports in 2009 reached 142.3Mt, up 4Mt from 2008, while total thermal coal exports increased 8Mt to 131.5Mt.