There is a large exiled Cuban-American population living in the United States, especially in and around Miami, FL and Union City, NJ. Those who oppose the communist government are represented in part by the Cuban-American lobby, which supports the U.S. embargo against Cuba and presses the communist government for political change. Other Cuban-American groups, some of which are anti-Communist, advocate different policies, opposing the embargo and favoring more cultural and economic engagement. Most prominent of these groups are the Brigada Antonio Maceo, Alianza Martiana, Miami Coalition Against the Embargo of Cuba, Alianza de Trabajadores de la Comunidad Cubana, Cuban American Defense League and Rescate Cultural AfroCubano. The Cuban government accuses Miami-based exiles of organizing over 700 armed incursions against Cuba over the past 40 years such as  machine-gun attacks on the Guitart Cayo Coco Hotel by Alpha 66 in 1994 and 1995. The Cuban government has long contended that some South Florida Spanish-language journalists are paid by the U.S. government. On September 8, 2006, it was revealed that at least ten South Florida journalists,  veteran reporters and a freelancer including some associated with the El Nuevo Herald, received payments totaling thousands of dollars over several years from the U.S. government for programs on Radio Martí and TV Martí, broadcasts aimed at undermining the Cuban state. In November 2006, U.S. Congressional auditors accused the development agency USAID of failing properly to administer its program to promote democracy in Cuba. They said that USAID had channeled tens of millions of dollars through exile groups in Miami, which were sometimes wasteful or kept questionable accounts. The report said the organizations had sent items such as chocolate and cashmere jerseys to Cuba. Their report concluded that 30% of the exile groups who received USAID grants showed questionable expenditures.

Based on the above article, answer a question. USAID was accused of questionable expenditures by whom?
U.S. Congressional auditors