BEAUMONT (AP) — U.S. prosecutors say two Greek shipping companies must pay a $4 million fine for not reporting illegal oil discharges by a tanker operating last year in Texas ports.

Avin International LTD and Nicos I.V. Special Maritime Enterprises pleaded guilty Monday in Beaumont to obstruction of an agency proceeding, failure to report discharge of oil and three counts of negligent discharge of oil.

Investigators say the Nicos I.V. in July 2017 discharged oil from its ballast system into the Port of Houston and the Port Arthur area.

The companies, in the plea deal, agreed to four years of probation and must implement an environmental compliance plan. Two crewmembers who pleaded guilty to making false statements to the Coast Guard could each be sentenced to five years in prison.