CALGARY -- The latest regulatory battle concerning a cross-border energy pipeline has broken out between two branches of the federal government.

The Canada Energy Regulator has fired off a warning letter to the Canada Border Services Agency over "non-compliance" with its pipeline regulations.

The complaint concerns a natural gas line that connects to a CBSA customs building on the Canada-U.S. border about 30 kilometres south of the community of Climax, Sask.

Because the "pipeline" runs from a meter on the building to the international border, it is regulated by the CER, the successor to the National Energy Board.

The letter accuses the CBSR of failing to appoint an "accountable officer" with authority over staff to ensure proper management of the pipeline, as well as not submitting its required annual reports on time.

CER spokeswoman Chantal Macleod says the border agency could face monetary penalties if it continues to fail to follow the rules.

"This written warning may be taken into account during the CER's compliance and audit planning (meaning the CBSA could be inspected or audited as a result)," she said in an email.

"If there are future non-compliances, the CER could consider further enforcement action, including an administrative monetary penalty."

A spokesman for the CBSA said he could not provide immediate comment on the case.