WASHINGTON - The United States on Wednesday strongly denounced a violent crackdown on protesters in Egypt, where at least 149 people have been killed when the police were trying to disperse two major sit-ins in the capital of Cairo.

"The United States strongly condemns the use of violence against protesters in Egypt," White House spokesman Josh Earnest said in a statement. "We extend our condolences to the families of those who have been killed, and to the injured."

More than 1,400 others were injured in violent clashes that broke out across Egypt after security forces moved in to break up supporters of Egypt's first elected President Mohamed Morsi, who was deposed by the military on July 3. His followers have been encamped in two Cairo squares demanding his reinstatement.

Hours after the raids, Egypt's interim president declared a state of emergency nationwide for one month, imposing a curfew on Cairo and 10 provinces and allowing security forces to arrest and detain civilians indefinitely without charge.

Earnest said, "We have repeatedly called on the Egyptian military and security forces to show restraint, and for the government to respect the universal rights of its citizens, just as we have urged protesters to demonstrate peacefully."

"Violence will only make it more difficult to move Egypt forward on a path to lasting stability and democracy, and runs directly counter to the pledges by the interim government to pursue reconciliation," he added.

Washington has opted not to label Morsi's ouster a coup, enabling it to continue its 1.3 billion dollars in annual aid to the Egyptian military. It, however, has halted the delivery of four F-16 fighters to Cairo in a show of its unhappiness with the military's handling of the situation.

"We also strongly oppose a return to a State of Emergency law, and call on the government to respect basic human rights such as freedom of peaceful assembly, and due process under the law," said Earnest.

"The world is watching what is happening in Cairo," he noted. " We urge the government of Egypt -- and all parties in Egypt -- to refrain from violence and resolve their differences peacefully."