REGENCY CRUISES <SHIP> SELLS SHIP INTEREST Regency Cruises Inc said it agreed to sell a 40 pct interest in the corporation that owns the M/V Regent Sea cruise ship for 2.1 mln dlrs to Monmouth International SA, which owns the other 60 pct. The company said it also extended a 1.7 mln dlr secured loan to Monmouth to finance completion of the renovation of another vessel, the M/V Regent Star, which is scheduled to begin operating in late June. Regency Cruises, which operates both ships, received a five-year extension, to November 1995, to the Regent Sea's original charter agreement, it said. It also received a reduction, to 600,000 dlrs from 1.6 mln dlrs, of its total charter guarantee for the Regent Sea and Regent Star. Regency also reported 1986 earnings of 5,695,000 dlrs or 37 cts a share on revenues of 40.9 mln dlrs. It began operations in November 1985. In addition, the company said its bank, Irving Bank Corp <V>, agreed to waive a one mln dlr counter guarantee for the bank to provide a 2.6 mln dlrs guarantee for Regency's Federal Maritime Commission bond. The company said after April 3 the exercise price of its warrants will return to two dlrs until they expire April 21. The price had been reduced to 1.50 dlrs for the three weeks ending April 3.