The UN's humanitarian chief held talks with Syrian officials on Wednesday to urge the regime to let let aid into devastated cities, with US President Barack Obama insisting military intervention would be a “mistake”. United Nations humanitarian chief Valerie Amos held talks in Damascus and was on her way to the devastated city of Homs Wednesday, a UN spokeswoman said. “She just completed a meeting with the MFA (Ministry of Foreign Affairs) and is now en route to Homs,” Elisabeth Byrs, spokeswoman of the UN Office for the Coordination of Humanitarian Affairs (OCHA), told Reuters in Geneva. Amos, who was denied entry to Syria last week, arrived in the country on a three-day mission to try to persuade authorities to grant unhindered access for aid workers to deliver life-saving assistance to civilians. The world body has been shut out of Syria, where the International Committee of the Red Cross (ICRC) is the only international agency allowed to deploy aid workers and provide food and medical supplies. But Syrian authorities continue to bar the ICRC from the embattled Homs district of Baba Amr, where UN Secretary-General Ban Ki-moon has voiced alarm at grisly reports that government forces have executed, imprisoned and tortured people. An ICRC aid convoy has been waiting to enter Baba Amr since last Friday, a day after rebel fighters fled the area following nearly a month of shelling by Syrian forces. The five major UN powers discussed on Tuesday new efforts to press for a halt to the violence in Syria, which Obama called heartbreaking, as regime forces pounded rebel towns and the death toll rose. However Obama cautioned that there was no simple solution in Syria, and warned that unilateral military action would be a mistake. He was speaking after top Republican Senator John McCain called for US air strikes on Syrian forces to protect population centers and create safe havens for opponents of the regime. “What's happening in Syria is heartbreaking, and outrageous, and what you've seen is the international community mobilize against the Assad regime,” Obama told a White House press conference. “On the other hand, for us to take military action, unilaterally, as some have suggested, or to think that somehow there's some simple solution, I think is a mistake.” Syrian President Bashar Al-Assad showed no signs of relenting in his crackdown on anti-regime elements, despite growing diplomatic pressure. The United Nations says the regime's crackdown has already cost over 7,500 lives in the past year, but Al-Assad vowed to press ahead with his campaign to crush “terrorism.” The United States, championing the diplomatic track, is leading work on a text for the badly divided UN Security Council, where Russia and China have twice used their powers as permanent members to veto Syria resolutions.