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　　BBC News with Stewart Macintosh

　　With fighting intensifying in the Syrian capitalDamascus, the latest diplomatic effort tostrengthen United Nations sanctions againstPresident Assad's government has failed. Russia andChina again vetoed a UN Security Council resolution proposing further sanctions as LauraTrevelyan reports from New York.

　　The British-drafted resolution would have renewed the mandate of the UN monitoring missionin Syria and sought to impose sanctions against President Assad's government if it continuedto use heavy weapons. All Western countries said this was the best way to increase pressureon Syria's rulers; Russia and China disagreed. Russia, a key ally of Damascus, said aresolution under Chapter 7 of the United Nations Charter could ultimately lead to militaryintervention in Syria.

　　The American ambassador at the UN, Susan Rice, said the US would now work outside the UNSecurity Council to bring pressure on the Syrian government. In Damascus, Syriangovernment troops launched sustained assaults on rebels as President Assad appeared ontelevision for the first time since the bombing killed three of his inner circle on Wednesday.Syrian state television showed Mr Assad swearing in a new defense minister while his forcesused tanks, heavy artillery and helicopter gunships against opposition fighters. Rebel sourcesreported many casualties.

　　Syrian opposition fighters have seized border crossings with Iraq and Turkey as Jim Muirreports from neighboring Lebanon.

　　Perhaps sensing that the regime was too preoccupied with the battle at the center, rebelfighters stormed all the border posts along the eastern frontier with Iraq. Iraqi officials said 22Syrian border guards were summarily executed after their post was overrun. At least twoother posts on the northern Turkish border were also reported to have been seized. Thedevelopments on the borders are likely to make it easier for the rebels to bring in more armsand fighters although Iraq's government, which is dominated by the Shiite majority and issympathetic to President Assad, has threatened to close it.

　　The Israeli Prime Minister Benjamin Netanyahu has blamed the Islamist group Hezbollah for thesuicide bombing of a bus full of Israeli tourists in Bulgaria on Wednesday. Mr Netanyahu saidthe group based in Lebanon was being sponsored by Iran.

　　"Yesterday's attack in Bulgaria was perpetrated by Hezbollah, Iran's leading terrorist proxy.This attack was part of a global campaign of terror carried out by Iran and Hezbollah. Iranmust be exposed by the international community as the premier terrorist-supporting statethat it is."

　　Iran has denied any involvement in the attack. The Bulgarian authorities say a white man withlong hair seen on video footage may have carried out the attack. Seven people died and morethan 30 were injured in the attack in the Black Sea resort of Burgas.

　　You're listening to the World News from the BBC.

　　The political parties who came second and third in Mexico's presidential election earlier thismonth are demanding an investigation into allegations that the winning party, PRI, usedlaundered money in its campaign. The PRI has rejected the accusation as 'flagrantdefamation'. The second placed candidate, Andres Manuel Lopez Obrador, has already filed alegal challenge to the election result.

　　The President of Guyana, Donald Ramotar, says there will be an investigation into the deaths ofat least three people during clashes on Wednesday. Demonstrators protesting against risingelectricity prices in the town of Linden said police had fired bullets and tear gas into the crowd.Protesters burnt down a local electricity plant and the offices of the governing party. They sayrampant poverty and high unemployment make it impossible for them to pay more for theirelectricity.

　　British immigration and passport control staff are to go on strike on the eve of the LondonOlympics in a dispute about pay and job cuts. The action is expected to cause particulardisruption to people flying into London for the games. Their day-long stoppage will be followedby a three-week overtime ban. The Home Secretary Theresa May condemned the strike.

　　"I think that is shameful, frankly. They are holding a strike on what is one of the key days forpeople coming into this country for the Olympic Games. I believe it's not right for them to holda strike. They will risk damaging people's enjoyment of coming through into the UK. We will ofcourse put contingency arrangements in place to ensure that we can deal with people comingthrough the border as smoothly as possible."

　　The Olympic tennis champion, Rafael Nadal, has pulled out of the London Games, saying he'snot in condition to compete in the tournament. He also said he would not attend the Gameswhen he was due to be the flag-bearer for Spain during the opening ceremony. Rafael Nadalhasn't played since he was eliminated in the second round of Wimbledon to the 100th rankedLukas Rosol.

　　And that's the latest BBC News.