Dozens of New Zealand academics, human rights workers and intellectuals have written an open letter to prime minister Jacinda Ardern urging her to protect the safety of a China academic who has been subjected to a year of burglaries and harassment.

Anne-Marie Brady, an expert in Chinese politics at the University of Canterbury in Christchurch, had her home and office burgled in February, and her car sabotaged this month.

Brady says she became a target after the release of a paper on Chinese foreign influence last year.

The 29 signatories to the letter said they had been “shocked and disturbed” by the incidents against Brady, and “academics must be able to work without fear”.

“Attempts to intimidate and harass one academic in New Zealand have implications for the freedoms of all the others – and indeed, for the freedoms of all who live here.”

The letter, also addressed to foreign minister Winston Peters, urged the government to take the threats against Brady “more seriously … in consideration for their implication for all New Zealanders”.

“We also urge prime minister Jacinda Ardern to make a clear statement in defence of academic freedom in New Zealand in light of the Brady case, and to be very clear that any intimidation and threats aimed at silencing academic voices in this country will not be tolerated.”

Signatories to the letter included the executive director of Amnesty International New Zealand Tony Blackett, Professor of International Relations at Otago University Robert Patman, and author and journalist Nicky Hager.

A spokeswoman for the prime minister said Ardern “supports and defends the legal right to academic freedom”, but it was not appropriate to comment further before the police investigation had been completed.

Last week Brady told the Guardian she and her family had requested security assistance from the government but it was not forthcoming.

“I am really concerned about the safety of my family. About four months ago we asked for more protection from the New Zealand security intelligence service … we haven’t had a reply,” Brady said.

“We are doing everything we can to improve security in our home. But New Zealand is a very open society … we’re just doing the best that we can by ourselves, but we’re not security specialists.”