Tropical storm Franklin strengthened to a category-one hurricane as it raged towards Mexico for a second assault on Wednesday, the US National Hurricane Center (NHC) said.

The NHC said in a report that Franklin was over the Gulf of Mexico 170 kilometers (105 miles) from the major port city of Veracruz.

Franklin struck Mexico's eastern Yucatan peninsula on Monday and was expected to make landfall again in the province of Veracruz in the coming hours.