Prime Minister Dr Mahathir Mohamad has expressed fear that a power struggle may emerge in his United Malays National Organisation (Umno) party after he steps down, a report said Sunday.

"I do not think there would be anyone who will challenge Abdullah Ahmad Badawi. But until the issue of (who becomes the) deputy president of Umno is resolved, there will be a power struggle for the number two post," Mahathir was quoted as saying in the Malay-language daily Mingguan Malaysia.