MEXICO CITY, April 27 (Reuters) - Mexican mining, rail and infrastructure company Grupo Mexico said on Wednesday its first-quarter net profit rose 20.9 percent compared to the same period last year.

Grupo Mexico posted a profit of $406.90 million for the three-month period, up from $336.52 million in the same quarter a year earlier.

Revenue for the quarter was down 7.8 percent at $1.9 billion as the company grappled with lower prices for some of its key commodities, including copper and silver.

(Reporting by Gabriel Stargardter and Anna Yukhananov)