HALIFAX -- Nova Scotia's labour minister says a series of rockfalls at Cape Breton's Donkin coal mine has prompted his department to bring in some international expertise.

Labi Kousoulis says mine inspectors from the U.S. Mine Safety and Health Administration will be looking into conditions at a section of the underground mine that experienced two roof collapses within a two-week period last month.

Kousoulis told reporters Wednesday the help is needed because there simply isn't the expertise available in Canada for a mine like Donkin, which operates under the seabed.

"We have been following all of the expert guidelines and we've exceeded code in terms of longer bolts shoring (the roof) up and we keep having falls, which every time it happens is a concern," he said.

Under department orders, mine operator Kameron Collieries must now use six-metre bolts to further stabilize the mine's roof and must also conduct more monitoring of roof conditions. The bolts at the mine have increased over time from just under two metres in length to the current requirement.

Kousoulis said his first concern is for the safety of the mine's workers. To date none of the rockfalls have resulted in injuries.

The minister said while he does consider the mine one of the most dangerous work sites in the province, the government isn't considering closing the operation.

However, he repeated a past warning that the situation could change if the safety problems can't be solved over time.

"If I get the indication that rockfalls will continue to happen in the future, then the conversation will be if we can't mitigate it then why are we operating the mine?" he said.

A provincial stop work order put in place after the most recent rockfall at the mine on Feb. 13 was partially lifted last Friday, with work allowed to resume in the area of the mine that wasn't affected by the collapse.

The latest rockfalls follow a roof collapse in July 2019, as well as two other rockfalls in December 2018.

This report by The Canadian Press was first published March 11, 2020.