Sydney: Australian customs officials destroyed two irreplaceable plant specimens that were being loaned to scientists by international institutions, prompting the agriculture department to concede that some missteps had occurred enforcing strict quarantine laws.

France’s National Museum of Natural History and New Zealand’s Landcare Research Allan Herbarium had sent the samples of lichen specimens, which dated back to the 19th Century, to Australia to help research, but they were intercepted by customs officers due to inaccurate paperwork.

A spokesman for the Department of Agriculture said the packages did not give any indication of the intrinsic value of the samples, and the customs officers held onto them for longer than they were required before deciding they posed a potential biosecurity threat and incinerating them.

“The department concedes the unintentionally proceeding with destruction of the specimens was premature,” a spokesperson for the Australian government department said in an emailed statement.

“But it does highlight the importance of the shared responsibility of Australia’s biosecurity system, and the need for adherence to import conditions.” Neither the French or New Zealand institutions were informed of the decision to destroy their lichen. Nor were the Australian scientists who were due to receive the samples. Normally a sender or recipient would be informed if there was a threat to destroy imported items.

Michelle Waycott, professor of plant systematic at the University of Adelaide and chair of the Council of Heads of Australasian Herbaria, said the specimens were set to be used to determine whether new plant species had been discovered in Australia.

“These specimens are also the last remaining evidence that they were present in a particular location,” said Waycott.

New Zealand’s Allan Herbarium has suspended all transfers to Australian scientists, until it can be sure that they can be safely received, Waycott said.

The agriculture department has started a review into its procedures, according to the spokesman.

Australia’s border security laws are among the world’s toughest, being designed to protect its island ecosystem from exotic pests and diseases.

Australia’s agricultural exports, worth a record A$45 billion ($33.31 billion) are also threatened by invasive species.