WASHINGTON (AFP) - Ratings agency Standard & Poors warned Thursday that the fight over the US debt ceiling could exacerbate the global tensions arising from Europes troubled economies. S&P also reiterated that it could downgrade the US debt rating if politicians cannot reach a deal to raise the countrys debt ceiling by August 2. We believe any additional stresses caused by a protracted standoff in the US would likely amplify already tense market conditions in Europe in light of significant fiscal imbalances in Greece, Portugal, and Ireland, the ratings agency said. Clearly, a default by the US government... could be substantially more serious, it said, comparing the impact to the global financial implosion of 2008. In contrast with then, however, most European countries are today in a far weaker fiscal position and, in our view, less able to provide substantive economic stimulus. The warning came as the White House said Thursday it saw momentum toward a pact to avert a disastrous early August debt defaultthough it cautioned against reports of an imminent deal. We still believe that the risk of a payment default is small, though increasing, S&P said. On July 14 S&P warned that it might cut the countrys top triple-A rating because of the standoff between President Barack Obamas White House and Republican opponents over the gaping budget deficit and the debt ceiling.