Federal agents detained 25 federal police officers in the northern border state of Tamaulipas on suspicion of providing protection for the Gulf drug cartel, the Public Safety Department announced, one week after soldiers carried out the biggest cocaine seizure in the nation's history there.

It was unclear whether the detention Friday of the 22 men and 3 women — all members of the Regional Security force, formerly known as the Federal Highway Police — was somehow related to the record seizure of nearly 12 metric tons of cocaine found packed in a freight container last week.

The officers were detained as they reported for work in the Gulf coast city of Tampico, and were then flown to Mexico City; they were being held on presentation orders — a kind of summons — and may face counts of drug trafficking, weapons possession and organized crime, the Public Safety Department said in a press statement.

Investigations into possible links between police and the Gulf drug cartel — which is believed to have owned the cocaine seized in last Friday's raid — began in May, when a a raid by federal agents on a drug trafficker's home in Tamaulipas turned up evidence linking a former federal highway police officer to the drug trade.

The investigations revealed that the former officer had "a close relationship" with current officers "who maintained a network of protection for the Gulf cartel," according to the statement.