ST. CATHARINES, Ont. -- More than a dozen people have been arrested following a yearlong investigation into what police are calling an international drug trafficking ring based in southern Ontario.

The arrests came early Monday as about 200 officers from across Ontario executed 30 search and arrest warrants in several communities, including Barrie, South Simcoe and Peel and Niagara regions.

Niagara regional police say they began an investigation in late 2013 into the activities of a drug trafficking ring based in the Niagara and Peel regions.

The investigation was expanded in February to include the Canada Border Services Agency, Ontario Provincial Police, RCMP in Hamilton, London and Toronto, and Peel regional police.

Police say the investigation -- which became known as Project Roadmaster -- uncovered evidence of cocaine importation and trafficking, money laundering and participation in a criminal organization.

Thirteen southern Ontario residents and one Mexican have been arrested on charges including narcotics, conspiracy and criminal organization-related offences.

Police say the investigation is ongoing and more arrests are expected.