Yemen's Nobel Peace Prize winner has been denied entry to Egypt.

Tawakkul Karman arrived in Cairo on Sunday morning, but was detained at the airport and prevented from travelling to Adaweya Square.

Airport officials say she was blocked from entering for "security reasons."

She is now returning to the Yemeni capital.

She told Al Jazeera that authorities are concerned she will tell the truth about what's going on inside Egypt.