Fighting intensified in the Yemeni capital, Sana'a, Friday hours after embattled President Ali Abdullah Saleh returned to the country from months of medical treatment abroad.

Loyalist troops fired on anti-government protesters in ''Change Square” Friday where thousands have been camped out for months.

Protests against Mr. Saleh have escalated over the past week, with clashes leaving 100 people dead since Sunday.

The embattled president arrived in Yemen from Saudi Arabia, where he spent three months recovering from injuries sustained in an attack on his presidential compound in Sana'a.

Supporters of Mr. Saleh honked their car horns and shouted slogans after his arrival in the Yemeni capital around dawn Friday.

In a statement after his return, the president said the solution to Yemen's mounting anti-government unrest was dialogue — not “guns and cannons.” He urged government and opposition forces to observe a truce and ceasefire.

In recent days, Yemen's political parties said they were working on a plan to force Mr. Saleh out of power.

Earlier this week, representatives of the six-nation Gulf Cooperation Council met with Vice President Abed Rabbo Mansour Hadi in Sana'a in an attempt to revive a long-stalled plan that calls for President Saleh to hand over power to a deputy.

The U.S. White House on Friday urged Mr. Saleh to begin a “full transfer of power.”