The United States is working with international donors to realise supply of electricity from energy-rich Central Asian region to Afghanistan and Pakistan, a senior US official said Tuesday. Richard Boucher, the top US official for South Asia, told a Congressional hearing that trade in electricity can benefit both sides, providing "much-needed energy to South Asia and serving as a major source of future revenue for the countries of Central Asia." "Together with other donors, we are also exploring ways to export electricity from Central Asia beyond Afghanistan to Pakistan and eventually India." In his prepared statement before a House sub-committee on foreign affairs, the US Assistant Secretary of State for both regions said the US is advocating for the countries of Central Asia to supply power to northern Afghanistan, and helping to develop the Afghan electricity system so Afghans can benefit from that connection. Continuing on efforts to foster economic and trade ties between the two regions, Boucher referred to August 2007 opening of a new bridge spanning the Pyanzh River that now connects Tajikistan and Afghanistan. "The bridge is an important piece of a future regional highway network extending from Karachi, Pakistan to Astana, Kazakhstan, including a network of more than 2,400 miles of roads within Afghanistan that have been constructed or reconstructed since 2001." Already, since the bridge opened, Afghan vehicle traffic to Tajikistan has increased seven-fold and border tax revenue ten-fold, he added.