Yemeni opposition tribal chief Sheikh Sadiq al-Ahmar urged the king of Saudi Arabia to prevent President Ali Abdullah Saleh's return to the country from Riyadh where he is undergoing medical treatment, Al Basheer news website reported on Wednesday.
Al-Ahmar said in a letter to King Abdullah bin Abdul-Aziz that if the president returns to Yemen, it would trigger a civil war in the country.
Arab media quoted Sanaa Deputy Mayor Yaser Yamani earlier in the week as saying if everything goes well, Saleh will return from Saudi Arabia to Yemen on Friday.
According to Arab media, Saleh's plane has already arrived at a Riyadh airport in preparation for departure to Sanaa.
Saleh was transported to Saudi Arabia for medical treatment after being injured in a rocket attack on his presidential palace in the Yemeni capital in early June. The attack on a mosque inside the palace, where Saleh and top government officials were attending Friday prayers, killed at least three bodyguards and wounded several senior officials.
The news about Saleh's return triggered mass protests among Yemeni opposition activists, who have been calling for his dismissal for the past five months.
Over 100 Yemeni tribal and religious leaders signed a petition calling for presidential elections within 60 days.
Saleh's supporters however announced nationwide preparations to greet the president.