About 7,000 servicemen from Yemen's Republican Guard and elite security forces joined the opposition, Al Arabiya said on Sunday citing a rebel general.
General Ali Mohsen al-Ahmar, who joined the Yemeni opposition in March to oust president Ali Abdullah Saleh, said the defected troops will under his command protect civilian protesters from government forces.
The rebel general was speaking with leaders of the Anes tribe, who also joined the opposition recently.
Saleh said last week he was going to resign "in the coming days," but will never hand over power to the opposition.
Mass anti-government rallies have been going on since February in Yemen. Demonstrators have demanded reforms and the resignation Saleh, who has led the country for more than 30 years. Washington has urged the Yemeni president to yield to the opposition's demands.
Negotiations between the government and the opposition on a plan presented by the Gulf Cooperation Council (GCC) broke down in the middle of September.
