In the capital, tens of thousands of protesters poured into a main square near Sanaa University chanting "Out, out!" and "God bears witness to your acts, Abdullah," an AFP correspondent reported. Organisers said the crowd swelled to 100,000.
Police set up checkpoints after Saleh ordered his forces Thursday to offer "full protection" to anti-regime protesters and loyalists alike.
In the past week two people have been killed in clashes with Saleh loyalists in Sanaa, while one was killed in similar violence in Taez, south of the capital.
The protesters have dubbed Friday "the beginning of the end" for Saleh`s regime which has been in power since 1978.
"There is no solution unless the regime steps down," prayer leader Sheikh Abdullah Satar told the faithful over a megaphone.
Clashes broke out in the southern city of Aden as thousands marching from several neighbourhoods towards the tightly patrolled Al-Aroob square in Khor Maksar were confronted by security forces who fired tear gas and bullets to disperse them, witnesses said.
Medics said seven people were wounded in Mualla neighbourhood while another two were hurt in Al-Memlah neighbourhood.
Almost daily clashes between police and protesters have killed 12 people in Aden since February 16, according to an AFP tally based on reports by medics and witnesses.
Meanwhile, also in the south, anti-Saleh demonstrators clashed with militants from the Southern Movement in Hadramawt who were carrying banners calling for the secession of the country`s formerly independent south, witnesses said.
No casualties were reported.
The president has resisted pressure to resign but has promised not to seek re-election when his current term ends in 2013 and has promised political reforms. (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2011