HELENA, Mont. (AP) — Montana is being challenged in court by a milk wholesaler that doesn't like the state's new sell-by rules.

Lee Newspapers of Montana reports California-based Core-Mark International Inc. has asked the state District Court in Helena to strike down the Board of Livestock's 12-day "sell-by" rule.

The board voted in May on the rule, the latest development in a long battle.

Core-Mark argues the 12-day rule has "no public health significance" and does nothing to protect consumers' safety.

It contends processors are already rigorously testing their milk — and argues that Montana is virtually alone among states that require a specific "sell-by" date.

It wants the state to follow 2011 recommendations of a hearing officer, who recommended a repeal of the 12-day sell-by rule.

The Board of Livestock declined to comment.