Sept 4 (Reuters) - Here is a snapshot of Reuters news about the crisis in Syria:
* President Barack Obama issues a blunt challenge to sceptical U.S. lawmakers to approve his plan for a military strike on Syria, saying they would put America's international prestige and their own credibility at risk if they did not.
* Russia says a military strike on Syria could have catastrophic effects if a missile hits a small reactor near Damascus that contains radioactive uranium. The Foreign Ministry in Moscow calls on the U.N. nuclear agency to urgently assess the risk as the United States considers military action to punish Syria's government for an alleged gas attack.
* U.S. Defense Secretary Chuck Hagel tells U.S. lawmakers a planned military strike on Syria would not be a "pin prick" and would significantly reduce President Bashar al-Assad's military power.
* The U.S. Senate Foreign Relations Committee struggles to reach agreement on a resolution authorizing military strikes in Syria, but schedules a vote for later on Wednesday.
* Russian President Vladimir Putin says U.S. Congress has no right to approve the use of force against Syria without a decision from the U.N. Security Council, and that doing so would be an "act of aggression". He also accuses U.S. Secretary of State John Kerry of lying to Congress about al Qaeda's role in the Syrian conflict.
* The Russian Foreign Ministry says a Russian expert report shows a makeshift weapon used in a chemical attack near the Syrian city of Aleppo in March was similar to ones made by rebel.
* A Hezbollah official said in a phone call intercepted by German intelligence that Assad had made a mistake in ordering a poison gas attack last month, suggesting the Syrian leader's culpability, participants at a security briefing for German lawmakers say.
* Putin says Russia may approve a military operation in Syria - if Damascus is proven to have carried out chemical weapons attacks, but he says such an operation could only be conducted with U.N. approval. At the same time, Putin says Russia will fulfill its arms contracts with Syria.
* Obama says he hopes Putin will change his position on Syria. "I'm always hopeful, and I will continue to engage him," he told a news conference in Sweden.
* Former Syrian Defence Minister General Ali Habib, a prominent member of Assad's Alawite sect, has defected and is now in Turkey, a senior member of the opposition Syrian National Coalition tells Reuters. Syrian state television denies this, saying Habib has not left the country. Habib would be the highest-ranking Alawite figure to break with Assad since the uprising against him began in 2011.
* The Syrian refugee crisis may worsen if there is no international response to the alleged chemical weapons attack, Turkey's Foreign Minister Ahmet Davutoglu says.
* Turkish Prime Minister Tayyip Erdogan reiterates that Turkey will take part in any international coalition against Syria, but stops short of saying whether its involvement would include military action.
* France's Prime Minister Jean-Marc Ayrault says if there is no response to the chemical attack in Syria this risks sending Iran the wrong message on its nuclear programme.
* British Prime Minister David Cameron says he believes the Syrian government will use chemical weapons against its own people again if the United States steps back from taking military action.
* The U.S. Congress, which votes largely along party lines on most issues, is displaying a different kind of split in the debate over Syria: Experienced lawmakers who support Obama's plans for military action are lining up against more skeptical and rebellious newcomers mostly from the ideological edges of both parties.
* Shifts of power and money - led by capital flight from emerging markets - and gaping divisions over Syria will test the resolve of G20 leaders when they meet in Russia's second city of St Petersburg this week.
* "My credibility is not on the line. The international community's credibility is on the line. And America and Congress' credibility is on the line, because we give lip service to the notion that these international norms are important." - U.S. President Barack Obama
* "Anything that is outside the U.N. Security Council is aggression, except self-defence. Now what Congress and the U.S. Senate are doing in essence is legitimising aggression. This is inadmissible in principle." - Russian President Vladimir Putin
* "The Middle East is a powder keg and the fire is approaching ... We shouldn't just talk about a Syrian response, but what will happen after the first strike. Everybody will lose control of the situation when the powder keg blows." - Syrian President Bashar al-Assad
* Global equity markets rise, lifted by a surge on Wall Street, and gold prices ease on expectations that any American military strike against Syria will be limited and data from around the globe suggesting a growing world economy.
* The Dow Jones industrial average was up 95.72 points, or 0.65 percent, at 14,929.68. The Standard & Poor's 500 Index was up 12.81 points, or 0.78 percent, at 1,652.58. The Nasdaq Composite Index was up 33.99 points, or 0.94 percent, at 3,646.60.
* The dollar drops against the euro for the first time in six sessions and retreated from a six-week high against a basket of currencies as data reflecting a growing world economy boosted investors' risk appetite.
* Brent crude weakens as it appeared that a military strike against Syria would remain limited, quelling fears of supply disruptions in the Middle East.
* Gold falls nearly two percent as investors cash in ahead of a crucial non-farm report that will give clues on the timing for the Federal Reserve's tapering, and on speculation that a U.S. strike on Syria is not imminent.
* Obama due in Russia for a two-day G20 summit that starts on Thursday.
* European Union Defence Ministers meet in Vilnius for two days from Thursday (Compiled by David Brunnstrom)