United Airlines said Tuesday it will begin daily service from Washington to Accra, Ghana, on June 20.

That will make it the second U.S. carrier to fly nonstop to Africa, joining Delta Air Lines.

"With the addition of service to Accra, United now offers customers nonstop service to points on six continents," said Mark Schwab, United's senior vice president of alliances, international & regulatory affairs.

"We look forward to offering service to Lagos - subject to approval by Nigerian officials - which will enable our customers to travel between Lagos and Washington more quickly and conveniently," he said.

The new flights will put United in a very small club, joining Delta as the only U.S. carriers to offer flights to six continents.

American Airlines and Continental Airlines fly to four continents, with no flights to Africa or Australia, although Continental Micronesia serves Cairns, Australia, from Guam.