World leaders expressed shock and horror after a gunman massacred 20 small children and six teachers Friday in the U.S. state of Connecticut, one of the worst school shootings in history.

U.N. chief Ban Ki-moon wrote to Connecticut Governor Dan Malloy to give his "deepest condolences at the shocking murders," a statement said.

Venezuela warned Friday that remarks by U.S. President Barack Obama describing the policies of ailing President Hugo Chavez as "authoritarian" could seriously harm already strained bilateral relations.

Caracas "strongly rejects the outrageous remarks by U.S. President Barack Obama regarding President Hugo Chavez and Venezuela," said Communications Minister Ernesto Villegas, reading a statement from the Miraflores presidential residence.

A heavily armed young gunman slaughtered 20 small children and six adults at a school in an idyllic Connecticut town on Friday, in one of the worst mass shootings in U.S. history.

Connecticut State Police spokesman Lieutenant Paul Vance said 18 children were shot dead inside Sandy Hook Elementary School and that two more died of their wounds in hospital.

President Barack Obama proclaimed Syria's newly reframed opposition as the "legitimate" representative of the nation's people Tuesday, in the most significant U.S. intervention in a brutal civil war.

As Washington cranked up pressure on beleaguered President Bashar Assad, the Obama administration also blacklisted the al-Qaida-linked Al-Nusra Front, which officials here fear seeks to hijack the revolution, as a terrorist group.

President Barack Obama on Friday asked Congress for $60.4 billion in emergency funds to repair devastation from Superstorm Sandy, which paralyzed the U.S. east coast when it hit in October.

"In total, the administration requests $60.4 billion in federal resources for response, recovery and mitigation related to Hurricane Sandy damage in all affected states," said Jeffrey Zients, White House deputy director for management.

U.S. President Barack Obama expressed "deep concern" Thursday over the recent deadly political protests in Egypt, in a call to his counterpart Mohammed Morsi, the White House said.

Obama also told Morsi that it was "essential for Egyptian leaders across the political spectrum to put aside their differences and come together to agree on a path that will move Egypt forward," the White House said in a statement.

Germany warned Syria Tuesday against any use of chemical weapons, ahead of a NATO meeting on Turkey's request for deployment of Patriot missiles to counter a potential threat from its neighbor.

"I can only warn the Syrian regime: a use of chemical weapons would be totally unacceptable," German Foreign Minister Guido Westerwelle said ahead of the gathering of his NATO counterparts in Brussels.

U.S. President Barack Obama on Monday called on Russia to join him as an equal partner in updating a nuclear non-proliferation deal, after Moscow opted not to extend it earlier this year.

Russian officials said in October that they had notified Washington that the Nunn-Lugar program, which disposed of thousands of Soviet-era warheads and missiles, would not be extended when it expires in May.

President Barack Obama dramatically told Syria's President Bashar Assad Monday not to turn chemical weapons on his own people, following U.S. warnings his forces were mixing deadly sarin gas.

Obama publicly told the increasingly isolated Assad not to unleash the "worst weapons of the 20th century" in the 21st, capping a day of alarming American warnings on the Syrian regime's intentions.

U.S. President Barack Obama urged Congress Saturday to immediately extend a tax cut for middle class Americans, arguing the move will give 98 percent of families and 97 percent of small businesses certainty that will lead to faster economic growth.

"Congress can do that right now. They can give families like yours a sense of security going into the New Year," Obama said in his weekly radio and Internet address.