One of the world's biggest cruise operators, Royal Caribbean Cruises, has agreed to pay nine-million dollars in fines, after admitting that its ships dumped oil waste at sea, instead of processing it ashore.

The Miami-based company told a United States federal court it accepted responsibility for polluting the waters around Puerto Rico, as well as dumping oil into the Atlantic and Pacific Oceans.

The company's president Jack Williams said itdeeply regretted its crews' actions and attempts to cover up the illegal practices, which included keeping false records.

The dumping was discovered in 1994 after a surveillance operation by American coastguards.

About one-million dollars of the fine will be contributed to a conservation fund.