U.S. President Barack Obama says he is “appalled” by Syria's use of violence against its own people, after rights activists say an army attack on the central city of Hama killed at least 80 people.

The White House statement issued Sunday said the “horrifying” reports out of Hama are demonstrating the “true character” of Syrian President Bashar al-Assad's government. Mr. Obama vowed the United States will increase pressure on Mr. Assad and work with others to isolate the Syrian government.

Also Sunday, the European Union joined the chorus of condemnation, while Italy and Germany called for an urgent meeting of the United Nations Security Council to review the situation.

U.N. Secretary-General Ban Ki-moon called on the Syrian government to halt the use of force against its citizens immediately and respect their human rights.

A U.S. embassy official in Syria also condemned Sunday's attacks in Hama, calling it “warfare” against the Syrian people.

In addition to criticizing the assault, former Lebanese Prime Minister Saad Hariri said “silence on the international and Arab levels” about the situation in Syria is only leading to the loss of more Syrian lives.