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President Ali Abdullah Saleh, the embattled leader of Yemen, vowed on Sunday to fight "with every drop of blood" to remain in power.

He also told military commanders that the country faced disintegration - accusing his political opponents of hijacking pro-democracy protests in the capital Sanaa, Aden and other cities - in a bid to split the nation on the southern tip of the Arabian peninsula.

"We have vowed to defend the republican system, the unity and safety of the republic till the last drop of our blood," he said.

"There is an attempt to split the country into north and south."

Saleh, the ruler of North Yemen since 1978, assumed control of the republic of Yemen when the north and south were unified in 1990.

On Sunday, he described protesters' demands for him to hand over power as "illegitimate".

"We are trying in every way possible to deal with and overcome these difficulties democratically, through dialogue with all political leaders, but in vain," he said.

In recent years, Yemen has had to contend with civil war, a secessionist movement in the south and the armed Houthi clan fighting for greater autonomy in the west.

Saleh has said he will not stand in elections in 2013, yet pro-democracy protesters remain sceptical, says Al Jazeera's Hashem Ahelbarra, reporting from Sanaa.

At least 19 people have been killed in almost daily clashes since February 16, based on reports by medics and witnesses, but Amnesty International puts the toll higher at 27.

Most have been killed in the southern city of Aden, with two in Sanaa and one in Taez in the north.

On Sunday, five protesters were wounded in Mukala, as police dispersed a demonstration of students calling for the fall of the regime. Medics said one protester was shot, and four were beaten with batons.

Pressure on Saleh to bow out intensified on Saturday when the leaders of Hashid and Baqil, two of Yemen's most influential tribes, joined the protests, which had seen some 100,000 turn out across the country the day previously.

Source: Al Jazeera & agencies