Amateur video shows a growing column of fire and smoke over what is purportedly Homs, Syria.
Activists say Syrian troops are bombarding the city for the 11th day.
The violence continues unabated as international efforts to halt President Bashar al-Assad's crackdown on the uprising founder.
The United Nations human rights chief said Russia and China's recent veto of a resolution condemning the Syrian government had emboldened the regime.
Meanwhile, German Chancellor Angela Merkel endorsed the Arab League's stance that Assad must step aside.
(SOUNDBITE) (German) GERMAN CHANCELLOR, ANGELA MERKEL, SAYING:
"The Arab League has taken a firm position which clearly points out the human rights violations committed by the Assad government. The European Union supports this position and we will underline it through further sanctions."
The head of the league, Nabil Elaraby, is meeting with Merkel in Berlin.
(SOUNDBITE) (English) ARAB LEAGUE SECRETARY GENERAL, NABIL ELARABY, SAYING:
"The people in the street, whether in Tahrir square or any other squares in other capitals were asking for what? They were asking for what you in Europe have had for a long time, liberty, democracy, social justice, dignity and good governance."
Elaraby said he also hopes to discuss Palestinian issues during his visit.
Lindsey Parietti, Reuters
