The world's leading economies have pressed the US and Europe to swiftly resolve their fiscal challenges, warning that they threaten to harm global growth. Finance Ministers and central bankers from the Group of 20 leading developed and emerging nations vowed to do everything necessary to strengthen the world economy, reduce financial market volatility and generate jobs.The two-day talks in Mexico City focused on the eurozone's relentless debt crisis and the looming fiscal cliff in the United States, a set of automatic spending cuts and tax hikes that could impact global growth if they go in effect in January. The G20 said in a final communique, global growth remains modest and downside risks are still elevated.The statement cited possible delays in the complex implementation of recent policy announcements in Europe and a potential sharp fiscal tightening in the United States.The finance chiefs also voiced concern over Japan's own fiscal troubles, as well as slowing growth in emerging nations and additional supply shocks in some commodity markets.G20 officials urged the winner of today's US presidential election, pitting incumbent Barack Obama against Republican Mitt Romney, to rapidly act to reach a deal with Congress after the vote. IMF Managing Director Christine Lagarde said, the US leadership needs to address quickly the so-called fiscal cliff.The G20 statement said Washington will carefully calibrate the pace of its fiscal tightening so that public finances are placed on a sustainable long-run path while avoiding a sharp fiscal contraction next year.Spanish Economy Minister Luis de Guindos warned that the US fiscal cliff hung over the world like the Sword of Damocles.Since G20 summit in June, the IMF slashed its 2012 global growth forecast to 3.3 per cent, eurozone unemployment rose to a record 11.6 per cent in September and growth decelerated in emerging nations.