Christmas is always the hardest time of year for Australia Post - and last year was its busiest ever thanks to the boom in online shopping.

As a result, staff are grateful for the modest bonus they usually receive when the government-owned business turns a profit. Last year, they got $500 after Australia Post turned a $241 million profit.

It was, chief executive Ahmed Fahour said, ''a gesture of goodwill in recognition of employee performance''. This year, with a thumping profit of $281 million, staff expected something similar.

Instead the Communications Workers Union have branded Mr Fahour a Christmas Grinch, after he decreed the staff bonus would be a $100 voucher - to be spent at Australia Post stores.

Adding insult to injury, full-time staff will also get in the mail 100 60c stamps (part-timers will miss out). The vouchers and stamps will, Mr Fahour has said in a briefing to staff, begin arriving in the mail this week.

The Communications Workers Union say this year's Christmas bonus is in stark contrast to Mr Fahour's own salary. He received $2.77 million last financial year, of which $874,000 was a cash incentive payment. This incentive payment is, the union argues, a rather large bonus.

Asked about this year's bonus payment to staff, Australia Post's general manager of external affairs, Jane McMillan, said that while Australia Post had delivered strong results, ''the outlook for the business remains challenging''.

''Continued mail volume decline and the need to invest $2 billion in our parcels and retail network means we will continue to keep our costs constrained,'' she said.

Joan Doyle, a state secretary of the Communication Workers Union's postal branch, said Mr Fahour's bonus increased by a third last financial year. Meanwhile, the Christmas bonus decided on for all of his staff would fall, in some cases by 80 per cent this year, Ms Doyle said. Clay Lucas