CANBERRA, July 18 (Reuters) - Australia's Wilmar Sugar and Renewables is closing its eight sugar mills for up to 16 hours due to a strike on Thursday by unionised workers asking for a better pay deal, the company said.

Wilmar, owned by Singapore's Wilmar International, said the shutdowns would cost sugar cane growers revenue of around $2.3 million. Another strike was planned for July 24, it added.

Wilmar is Australia's largest sugar producer and makes more than 2 million metric tons of sugar worth around $1 billion a year, most of which is exported.

Industrial action beginning in May disrupted the start Wilmar's June-to-November cane crushing season, threatening sugar production, but strikes became less frequent from June.

Thursday's strike follows a successful appeal by unions against a government labour tribunal order to suspend industrial action, Wilmar said.

While the strike itself is only one hour long, Wilmar said the safe shutdown and restart of boilers and turbines took much longer.

Wilmar's mills form the economic centre of communities on the country's hot and humid northeast coast, where sugar is a major industry. (Reporting by Peter Hobson; Editing by Jamie Freed)