Tens of thousands of Yemenis gathered in different provinces across the country on Friday to demand an end to President Ali Abdullah Saleh's 33-year-long rule dpa reported
The protest follows overnight attacks by Saleh's forces upon areas where his opponents are stationed.
In the latest incident, pro-Saleh forces raided areas in Sana'a and villages in Arhab, north-east of the capital, leaving at least two people dead and dozens injured, opposition media reported.
Attacks on the Arhab region have increased lately as new villages have recently declared support for the anti-regime uprising, further decreasing tribal backing for Saleh.
Witnesses said that clashes also took place between anti-Saleh tribesmen and the president's loyalists in the area of Hasabah, which had seen intense fighting since influential tribal leader Sheikh Sadiq al-Ahmar announced support for protesters in May.
The US ambassador in Sana'a, Gerald M Feierstein, has called on Saleh to end his rule in order to allow for a smooth transition of power.
He added that the political process needs to move forward to bring about a political solution for the Yemeni stalemate, the opposition al-Sahwa weekly reported Thursday. Yemenis have taken to the streets since February, demanding an end to Saleh's 33-year rule.
At least 1,480 people were killed in the Arabian Peninsula country between February and September, according to government figures.