A troubled Chinese company has found a novel excuse for continuing to delay publishing its annual results, telling investors that a thief stole all its financial records for the last four years.

Hong Kong-listed China Animal Healthcare, which makes vaccinations and other drugs for livestock and poultry, said a truck carrying all its original financial documents for the period was stolen while the driver took a lunch break.

The "Lost Documents", as the company referred to them in a statement to the Hong Kong stock exchange, are at the centre of a forensic accounting investigation after China Animal Healthcare delayed releasing its 2014 annual results in March and auditors refused to sign them off.

Trading in its shares has been suspended for nine months because of the dispute.

"The board...of directors...of the Company wishes to inform the shareholders of the Company... that on 4 December 2015, a truck of the Group... loaded with, among other things, all original financial documents of the Group for the four financial years ended 31 December 2014 and for the current year... were stolen," the statement said.

"According to the local public security bureau, thefts such as the incident are common occurrence" in the Qingyuan area where the alleged crime took place, it added.

The driver was said to have been transporting documents stored at a facility in Hebei province to the company's headquarters in Beijing, but the truck was stolen when he stopped for lunch at a restaurant.

The firm is now trying to track down copies of the missing documents, it said, adding the suspension of its shares would continue "until further notice".

The truck was later found by local police but the thief had apparently made off with the documents, although they would have little value except to the company.

"Although the possibility of finding the Lost Documents is not high, the group has nonetheless deployed all possible resources in search of the Lost Documents," it said.