An email campaign is urging women to wear designer mini-skirts and ostentatious gold earrings to work today in protest at the sacking of one of New Zealand's top female civil servants.

Christine Rankin has taken the government to court in Wellington claiming unfair dismissal from her £72,000-a-year post as head of the work and income ministry, the largest government department in the country.

Despite the New Zealand government being headed by a female prime minister, Helen Clark, backed by seven female cabinet ministers, Ms Rankin claimed she was systematically discredited by attacks on her dress sense. She regularly wore expensive cream suits and pendulous earrings to work.

Headed "Women of the Workforce Unite," the email asks women to attend a protest outside the court and dress like Ms Rankin to "show the sexist men of this country we will not tolerate their oppression".

The public servant head of the prime minister's and cabinet office, Mark Prebble, told the court that he was embarrassed and "outraged" by Ms Rankin's plunging necklines. "Every time she moved I found that I was having to see an embarrassingly large amount of breast exposed."

He admitted advising her that public servants should dress in grey at work, preferably choosing off-the-peg attire "from a chain store".

The opposition leader, Jenny Shipley, has criticised Ms Clark for "condoning" the sexism of her male civil servants.

But women's solidarity with Ms Rankin has been tested by freezing winter temperatures. "I don't have a short skirt, I don't have dangly earrings and I don't have time for Christine Rankin," Nicola Sanders said. "I don't hold her in very high regard as far as her fashion sense goes."