Reports over the weekend indicated that a company associated with a planned high-speed rail line in Mexico owns a mansion that is occupied by the presidential family. The $ 7 million mansion is registered to Ingenieria Inmobiliaria del Centro, a firm owned by Grupo Higa, which is associated with a Chinese-led consortium that won a $3.75 billion rail contract last week.
The Mexican government subsequently revoked the rail contract, which was awarded through an uncontested bid, after an immediate outcry from Mexican lawmakers.
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Grupo Higa did not reply to requests for comment from CNBC. The allegations surrounding the president's mansion are based on documents first reported by the Spanish-language website Aristegui Noticias that were independently examined by the Financial Times.
The reports come as Mexico gets closer to auctioning the rights to joint ventures with state energy giant Pemex, a company that generates 18 percent of Mexico's tax revenue but which has seen its output plunge by 1 million barrels a day over the last decade.
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Mexico's Hydrocarbon Commission is overseeing the auctions, which are being watched widely by international energy and business interests and are expected to come in April or May.
Mexico has "an imperative to conduct a clean auction," Thompson said. "The government wants to keep this cash cow going, and one way to do that is to keep the energy sector productive in such a way that Pemex can remain an effective form of revenue for the Mexican government."