MEXICO CITY - Environmental activists have draped Mexico City's Independence Monument in black to protest approval of genetically modified corn plantings.

Members of Greenpeace Mexico have drapped black banners from the 35-meter (yard) tall column and placed black arm bands on statues of national heroes on the monument, which is topped by the image of an angel.

Protester Aleira Lara says "today, the angel of Independence is in mourning."

Mexico approved the first two experimental plantings of biotech corn Thursday in controlled areas where officials say no native corn varieties exist.

Protesters said Sunday that modified genes could spread and contaminate genetically valuable native varieties of corn, which originated in Mexico.