A Nicaraguan naval vessel on an evacuation mission went missing in the Caribbean on Monday as nearby Hurricane Rina took aim at the popular tourist resort beaches of Belize and Mexico.

Nicaraguan President Daniel Ortega had ordered the ship, with 27 rescuers and sailors on board, to evacuate flood-prone coastal areas when contact was lost, a military spokesman said.

It was one of three boats that had set out to help evacuate indigenous Miskito residents from Sandy Bay, a coastal town north of the provincial capital Bilwi.

Driving rains have drenched Nicaragua for the past 12 days leaving 16 people dead, and an estimated 150,000 homeless or evacuated. The hurricane has started to move away from the country but the missing sailors highlighted its danger.

"We are asking the Lord to help us save the lives of these people... and for them to get into port safely," said First Lady Rosario Murillo, who is also a spokeswoman for the government.

Rina strengthened into a hurricane on Monday in the western Caribbean, threatening to bring heavy rain and strong winds to an already waterlogged Central America and Mexico's Yucatan peninsula, US forecasters said.

It is now likely to barrel into Belize and Mexico's popular tourist coast on the Yucatan by the end of the week, the Miami-based National Hurricane Center said.

"Strengthening is expected during the next 48 hours and Rina could become a major (Category 3) hurricane by late Tuesday," it said.

Rina is currently a Category 1 storm on the five-level Saffir-Simpson wind scale and is packing maximum sustained winds near 75 miles (120 kilometers) per hour, with higher gusts, the NHC said.

The sixth hurricane and 17th named storm of the Atlantic hurricane season was heading northwest at 3 miles per hour (5 km/h), and is about 195 miles southwest of Grand Cayman island and some 360 miles east of Chetumal, Mexico.

Rina had spent days nagging the coastline of Honduras as a disorganized depression, then dramatically coalesced into a hurricane.

The NHC forecast that Rina would head directly over the popular Mexican tourist island of Cozumel and beach haven of Cancun on Friday.

Rina was forecast to dump up to four inches (10 centimeters) of rain on the Grand Caymans, with similar amounts on the mainland.

The US agency urged authorities in the Yucatan peninsula and in Belize to closely monitor the storm's path and send out warnings when appropriate.

Central America is still struggling to recover from recent torrential rains that triggered deadly flooding and landslides, swamped huge swathes of farmland, and caused hundreds of millions of dollars in damage.

The number of fatalities across the region topped 100, including 36 deaths in Guatemala, 34 in El Salvador and 18 in Honduras.