WASHINGTON - The Obama administration is looking for more ways to stop Iran from acquiring nuclear weapons and is encouraged by the help it is getting from Tehran's largest trading partners, Treasury Secretary Timothy Geithner said on Tuesday."We are going to keep looking at ways we can bring more pressure to bear," Geithner said at the House Financial Services Committee hearing to examine the state of the global financial system. "We are making really substantial progress, and our hope is of course that it will alter Iran's calculations about their interest in pursuing nuclear capabilities."Countries are scrambling to reduce their Iranian oil imports in order to avoid harsh US sanctions that are to kick in at the end of June. If countries fail to significantly cut their reliance on Tehran's oil, their financial institutions could be blocked from US markets.Under pressure from the United States, Europe has imposed similar penalties on Iran's central bank, and its regulators have ordered the biggest electronic payment system to block Iran's state-owned banks from using its network to help transfer funds.Geithner said support for US action extends far beyond Europe. "You're seeing Japan, South Korea, China and countries around the world really moving with us to tighten up" sanctions against Iran, he said.Saudi Arabia, the world's top oil exporter, has said it will fill any oil supply gap created by the loss of Iranian oil - a move that helped the price of Brent crude on Tuesday fall to around $124 a barrel. Geithner said the statement from Saudi Arabia was a "very constructive signal."