Democratic President Barack Obama and former President George W Bush are proving that it's a small world after all, with an extraordinary chance encounter a long way from home.

Obama and his Republican predecessor plan to appear together briefly today, when by coincidence both will be in the same city on Africa's east coast promoting development on the continent. Obama is on the final day of a weeklong tour of the continent, while the George W Bush Institute is hosting a two-day summit on African women.

Initially the two men had no plans to meet, but the White House announced yesterday that they would gather at a memorial for Americans killed in the US Embassy bombing here nearly 15 years ago. They plan to lay a wreath in honor of the 11 Americans who died in the attack masterminded by Osama bin Laden, along with a near-simultaneous bombing at the US Embassy in neighboring Kenya.