Tropical Storm Irene hit Puerto Rico early Monday as meteorologists said it was approaching hurricane strength on its path north-west up the Caribbean. The governments of Puerto Rico, the Dominican Republic and Haiti were on high alert and had closed schools, business and public transport for Monday. The storm was recording sustained winds of 110 kilometres per hour, at 1 am (0500 GMT) as it made landfall on Puerto Rico, the US National Hurricane Center said. It would probably reach sustained winds of 75 miles per hour, making it officially a hurricane, on Monday, the centre said. The storm, whose trajectory put it on a course towards Florida, would probably lose strength over the island of Hispaniola, consisting of the Dominican Republic and Haiti, the Miami-based centre said.