Obama's encounter with Karzai at Mandela memorial just a greeting: White House

ON BOARD AIR FORCE ONE (Reuters) - President Barack Obama's encounter with Afghanistan President Hamid Karzai at Nelson Mandela's memorial in South Africa was "just an exchange of greetings," a White House aide said on Tuesday.

White House deputy national security adviser Ben Rhodes told reporters aboard Air Force One during the return flight to the United States that Obama had not seen the venue as a place to do business with Karzai, who has rebuffed what he calls pressure from Washington to accept a new security agreement.

(Reporting by Steve Holland, writing by Jeff Mason)