Brazil and Mexico summoned U.S. ambassadors on Monday to demand explanations over allegations that the National Security Agency spied on their presidents' communications.

Brazil's Foreign Minister Luis Figueiredo said the interception of Internet data from President Dilma Rousseff reported by U.S. journalist Glenn Greenwald, if proven, "represents an unacceptable and unallowable violation of Brazilian sovereignty."

Russian authorities are planning to send a parliamentary delegation to the United States for talks with the Congress over Syria, in a move publicly endorsed Monday by President Vladimir Putin.

"The initiative is very timely and correct," Putin told speaker of Russia's upper house of parliament Valentina Matviyenko and speaker of the lower house of parliament Sergei Naryshkin.

Former Soviet leader Mikhail Gorbachev said Monday U.S. President Barack Obama was right to seek backing from Congress for military action in Syria, but warned that intervening raised dire risks.

Obama has faced criticism for alleged indecisiveness and for passing the ball to U.S. lawmakers after previously taking a hawkish tone over an alleged chemical attack in Syria.

Russia has sent a reconnaissance vessel from its Black Sea fleet to the coast off Syria, a report said Monday, as Moscow anxiously watches Western plans for military action against the Damascus regime, a report said Monday.

The SSV-201 intelligence ship Priazovye on Sunday evening started its voyage from its home port of Sevastopol in Ukraine "to the appointed region of military service in the eastern Mediterranean," a military source told the Interfax news agency.

Russia is totally unconvinced by evidence presented by the United States and its allies of an alleged chemical attack outside Damascus that the West says was perpetrated by the Syrian regime, Foreign Minister Sergei Lavrov said Monday.

Moscow vehemently opposes U.S.-led plans for military action against the regime of Bashar Assad in response to the alleged attack, even though the timetable has now been put back by President Barack Obama's decision to put it to Congress.

U.S. spy services conducted 231 "offensive cyberoperations" in 2011, mostly targeting Iran, Russia, China and North Korea, the Washington Post reported Saturday.

The revelation is based on a classified intelligence budget provided to the paper by fugitive leaker Edward Snowden, as well as on interviews with former U.S. officials.

German Chancellor Angela Merkel hit out at Russia and China over their stance in the Syrian crisis, saying in an interview published Saturday that their action weakened the United Nations.

"It is very regrettable that Russia and China have refused for some time to come to a common position (with Western partners) on the Syrian conflict. This considerably weakens the role of the United Nations," she said in an interview with regional daily Augsburger Allgemeine.

U.N. leader Ban Ki-moon on Friday met with U.N. ambassadors from Britain, China, France, Russia and the United States after cutting short a visit to Europe over the Syria chemical weapons crisis.

Ban has been pressing U.S. President Barack Obama and other world leaders not to allow a military strike on Syria until U.N. experts have finished their work in the country.

President Vladimir Putin has no plans for a bilateral meeting with U.S. President Barack Obama at the G20 summit next week but will greet him and "shake his hand," a Kremlin official said Friday.

With U.S.-Russia tensions reaching a new peak over the Syrian crisis and Moscow's decision to give asylum to U.S. intelligence leaker Edward Snowden, Putin's foreign policy adviser Yury Ushakov appeared compelled to note that Obama will be treated just like any other leader.

Poland's foreign minister on Friday said Russia was responsible for Syria's Soviet-era chemical weapons and could use its clout to impact the course of the country's conflict.

"Russia keeps stressing that it is against the use of chemical weapons, but we know the Syrian arsenal dates back to the days of the USSR. It's Soviet technology," Foreign Minister Radoslaw Sikorski told reporters in Warsaw.