WASHINGTON (Reuters) - The U.S. Senate on Thursday blocked an effort to prevent the $700 million sale of Lockheed Martin Corp (LMT.N) F-16 fighter jets to Pakistan, although a key lawmaker said he would not allow the use of U.S. funds to finance it. Lawmakers voted 71 to 24 against an attempt introduced by Republican Senator Rand Paul to prevent the sale under legislation known as the Arms Control Act. President Barack Obama’s administration announced on Feb. 12 that it had approved the sale to Pakistan of the aircraft, as well as radars and other equipment. It drew immediate criticism from India and concern from some members of Congress.  Paul had called Pakistan “an uncertain ally” and other lawmakers expressed concerns about Pakistan’s nuclear program, commitment to fighting terrorist organizations and cooperation in the Afghanistan peace process. However, they generally supported the sale, saying the South Asian state needs to modernize its air force and counter-terrorism activities. Republican Senator Bob Corker said he would use his power as the chairman of the Senate Foreign Relations Committee to bar the use of any U.S. funds for the deal. In a statement, Corker said, “Prohibiting a taxpayer subsidy sends a much-needed message to Pakistan that it needs to change its behaviour, but preventing the purchase of U.S. aircraft would do more harm than good by paving the way for countries like Russia and China to sell to Pakistan while also inhibiting greater cooperation on counter terrorism.” The United States identified Pakistan as a key partner in its war against terror following the Sept. 11, 2001, attacks and spent billions of dollars on military aid to help the country fight insurgents. But there is growing consternation in Washington about continuing with the same level of assistance unless Pakistan provides evidence it is using the funds effectively to eliminate militants. 