Embattled dairy co-operative Fonterra has slapped a pay freeze on its top-earning executives.

Chief executive Miles Hurrell has emailed staff that all salaried employees on individual contracts earning more than $100,000 will not be getting annual pay increases in the year ahead.

According to the 2018 financial report, more than 6000 of Fonterra's 22,000 staff were on salaries of $100,000 and over.

It had also been decided that bonuses for the short term incentive scheme or an NZMP business sales incentive plan would not be paid in the 2019 year, Hurrell said.

Salaried employees under this pay level would still get a pay review and there would be no impact on waged staff who are part of a collective agreement, he said.

The world's biggest exporter and New Zealand's only true global company will publish its annual results on September 12 after a shock asset writedown forecast of up to $860 million.

It is anticipating a loss of $590m-$675m.

The company has refused to say if there have been redundancies as a result of the internal business review and reset that unearthed the need for the asset writedowns.

Former chief executive Theo Spierings, who departed the company in August last year, earned $43 million in his seven years in the top job.