(Adds Aspire price move, updates numbers)
MELBOURNE, Jan 10 (Reuters) - Australian shares inched down 0.1 percent in midday trade on Thursday, retracing early gains as investors worried about a possible pullback in iron ore prices and waited on December trade data from China, Australia's top customer.
China's imports of crude oil, iron ore and soybeans are expected to have risen in December as confidence in the economy grew and buyers stocked up for 2013.
But investors were showing growing concerns about iron ore prices, which have shot up sharply since last September's low, said Credit Suisse's equity strategist Damien Boey.
"They don't believe the sustainability of it," Boey said. "There is a major restocking cycle of commodities which is going on in China, and they are not sure whether it will last."
"My suspicion is that it has to fall back because the restocking cycle is very seasonal," he added.
The benchmark S&P/ASX 200 index was down 2.6 points at 4,705.5 by 0145 GMT. It rose 0.4 percent on Wednesday to snap a three-day losing streak.
Top miners weighed on the market, with BHP Billiton Ltd dropping 0.5 percent and Rio Tinto Ltd losing 0.2 percent.
Banks were mixed, with Commonwealth Bank of Australia bouncing back 0.2 percent and Westpac Banking Corp easing 0.2 percent.
New Zealand's benchmark NZX 50 index edged up 0.2 percent to 4,110.2.
New Zealand posted a bigger-than-expected NZ$700 million ($583 million) trade deficit for November, its fourth straight monthly trade deficit..
* Australian construction firm Macmahon Holdings Ltd climbed 1.8 percent to A$0.28, having jumped as much as 5.5 percent after it received a revised offer from Sembawang Australia.
Sembawang, a subsidiary of India's Punj Lloyd Ltd, stepped up its offer for Macmahon's construction business on Thursday, looking to trump a current deal with Leighton Holdings Ltd.
* Miner Aspire Mining Ltd surged 69.5 percent to A$0.1, after Noble Group agreed to provide additional support for its coking coal project.
* Australia's biggest gold miner Newcrest Mining Ltd fell 2.1 percent to A$21.56, declining for a fifth session in a row to hit a near six-month low.
0143 GMT Reporting by Maggie Lu Yueyang; Editing by Jacqueline Wong