SAO PAULO, May 21 (Reuters) - Brazil's biosafety regulator CTNBio has approved the use of Monsanto's (MON.N) Bollgard 2 genetically modified cotton seed, the company said on Thursday 21 May.

The pest-resistant cotton variety must still be approved by Brazil's Agriculture Ministry before it can be planted in the country.

U.S.-based Monsanto has a total of six genetically modified varieties of cotton, soybeans and corn already approved for commercial planting in Brazil.

Bollgard 2 is a second-generation of pest-resistant cotton. It contains two different insect control genes, compared with the single insect control gene in its predecessor, Bollgard, which was approved in Brazil in 2005.

Other genetically modified cotton seeds developed by Bayer (BAYG.DE) and Dow Chemical (DOW.N) already have been approved for use in the South American country, a top producer of sugar, soy, coffee and oranges.

(Reporting by Roberto Samora, Writing by Inae Riveras)