US airlines and package-delivery companies suspended service to and from Haiti following a 7.0 magnitude earthquake that may have killed thousands of people.

Delta Air Lines, the world's largest air carrier, cancelled its flight from New York's John F Kennedy International Airport to Port-au-Prince, Haiti's capital, company spokesperson Anthony Black said.

AMR Corp's American Airlines flew its last flight from Haiti to Miami on Tuesday night around 6:45pm EST (2345 GMT), spokesperson Tim Smith said.

Both carriers said they were uncertain when flights to Haiti would resume.

Logistics companies United Parcel Service and FedEx confirmed their operations in Haiti were halted until the airport reopened to commercial traffic.

"We are holding our customers' shipments in Miami until we can resume operations," said Sally Davenport, a spokeswoman for FedEx.

Norman Black, a spokesman for UPS, said his company was also holding deliveries until it could resume flights into Haiti.

"We're not sure exactly when that's going to be with the status of the airport there," Black said.

Both companies also said they are working with international relief agencies to help transport supplies into the disaster zone.

The earthquake's epicentre was 10 miles from Port-au-Prince. Aftershocks as powerful as 5,9 rattled the city Tuesday night and Wednesday. About 4 million people live in the city and the surrounding area.

Meanwhile, cruise operators had quiet Haitian operations.

Royal Caribbean Cruises said its private beach destination in Labadee, Haiti, reported no apparent damage to the company's buildings, pier and attractions. It added that all of its workers in Labadee were accounted for and had no injuries.

No Royal Caribbean ships are set to call on Labadee on Wednesday. The company's Independence of the Seas cruise ship is scheduled to go to Haiti Friday. Three other ships are slated to stop in Haiti next week.

Carnival, the world's largest cruise operator, said it does not have any cruise ships scheduled to stop in Haiti and added there were no changes to its schedule.

JetBlue Airways said it would waive change fees and fare differences to allow customers to rebook their travel to the Dominican Republic, which shares the island of Hispaniola with Haiti.

The US State Department urged Americans not to travel to Haiti. - Reuters