Emergency crews on Tuesday scrambled to contain an oil spill near Athens after a tanker sank close to Salamis island over the weekend, the coastguard said.

Hurricane Irma weakened to a Category 1 storm early Monday as it marched up the .US. state of Florida's northwestern coast, with its eye located about 25 miles (40 kilometers) northeast of the vulnerable Tampa area.

The combined economic cost of Hurricanes Harvey and Irma could reach $290 billion, equivalent to 1.5 percent of the U.S. gross domestic product, U.S. forecaster AccuWeather said in a report Sunday.

"We believe the damage estimate from Irma to be about $100 billion, among the costliest hurricanes of all time," said the firm's CEO and founder Joel Myers. 

U.S. President Donald Trump approved Florida's request for emergency federal aid on Sunday to help with the recovery from destructive Hurricane Irma.

The federal funding includes "grants for temporary housing and home repairs, low-cost loans to cover uninsured property losses and other programs to help individuals and business owners recover from the effects of the disaster," the White House said.

Hurricane Irma's eyewall slammed into the lower Florida Keys Sunday, lashing the island chain with fearsome wind gusts, the U.S. National Hurricane Center said.

The eye of the Category 4 storm was 15 miles (24 kilometers) southeast of Key West as of 7:00 am local time (1100 GMT), bringing maximum sustained winds of 130 miles per hour and threatening dangerous storm surges.

Environmental ministers representing Canada, China and the European Union will co-host a meeting in Montreal later this month to move forward with the implementation of the Paris climate change agreement.

Hurricane Irma killed two people and wounded 43 others when it barreled through the Dutch part of the Caribbean island of Saint Martin, a Dutch official said Friday.

Hurricane Katia strengthened on Friday to Category Two storm on a scale of five as it raged towards the eastern coast of Mexico, authorities said.

Florida Governor Rick Scott warned Friday that all of the state's 20 million inhabitants should be prepared to evacuate as Hurricane Irma bears down for a direct hit on the southern U.S. state.

"The storm is powerful and deadly," Scott said. "Do not ignore evacuation orders.

King Willem-Alexander of the Netherlands will visit the island of Curacao on Sunday to witness first-hand the aid operation for hurricane-hit territories, and may travel to stricken St Martin, Dutch officials said.