MEXICO CITY, March 27 (Reuters) - Mexico on Tuesday kicked off its final energy auction before the July presidential election, tendering 35 shallow-water oil and gas blocks in a test of foreign producers' interest in investing amid uncertainty over energy reforms.
The first blocks awarded went to Spain's Repsol and Britain's Premier Oil in the Burgos basin in the violent state of Tamaulipas, with few other companies bidding. Blocks in two other basins will be awarded later in the day.
Leftist frontrunner Andres Manuel Lopez Obrador says that if he wins the July 1 vote he will review more than 90 contracts signed since Mexico passed legislation in 2013 ending the 75-year monopoly of state energy firm Pemex.
Lopez Obrador said this month that he will ask President Enrique Pena Nieto to cancel two auctions planned for the second half of the year, if he wins in July.
Mexico is competing for investment with Brazil, which is also holding an auction this week, with another scheduled in June.
Brazil holds its own election in October, with the most likely leftist contender in the presidential race, Ciro Ferreira Gomes, warning he would expropriate energy assets bought by investors if he wins.
In Thursday's auction, Mexico offered 35 areas in the Burgos, Tampico-Misantla-Veracruz and Southeast basins.
Fourteen companies including BP, Chevron, Eni, India's ONGC Videsh, Pemex, Petronas, Repsol, Shell and Total qualified to bid as individual bidders, while 22 consortia have also qualified to bid. (Reporting by Gabriel Stargardter Editing by Susan Thomas)