Officials say that Yemen's Nobel Peace Prize winner Tawakkul Karman has been denied entry into Egypt after she landed at Cairo airport.

Karman, the first Arab woman to win the Nobel Peace prize, has stated her opposition to the military coup that ousted fellow Islamist Mohammed Morsi on July 3 after days of mass protests in which millions of Egyptians demanded that he steps downs.

She said she had intended to join the larger of two sit-in protests by Morsi supporters in the Egyptian capital.

The Cairo airport officials said Tawakkul was sent back on the Sunday flight that brought her to Cairo from the United Arab Emirates.

The officials spoke on condition of anonymity because they were not authorized to speak to the media.

Karman was sent back on the same plane she flew in on, said the security sources.

Karman's Twitter feed on Sunday said the writer and activist had been held at Cairo Airport and prevented from joining protests. MENA said Karman was on a list of people who were not allowed to enter Egypt.

In Yemen they call her the "Iron Woman" and the "Mother of the Revolution."

Karman is a member of Yemen's leading Islamic opposition party, the Islah, a group that has caused alarm in the West, mainly because of its most notorious member, Abdul Majeed al-Zindani, a former Osama bin Laden adviser considered a
terrorist by the Americans.

The Egyptian army's overthrow of Morsi one month ago has plunged the country into political turmoil.