Robert Shapiro, chief of the St. Louis based company that hasdeveloped genetically enhanced soybeans, potatoes and other  crops, had just finished delivering a keynote address Tuesday night at a conference in San Francisco's glitzy Fairmont Hotel  when he was approached by a heckler. An official with the conference said that as Shapiro stopped to have a discussion with the heckler, he was ambushed by two activists wielding pies.

In a statement, a group calling itself the "Biotic Baking Brigade"(BBB) said two "field agents" threw a tofu creme pie and a sweet potato pie at Shapiro. The tofu creme hit him in the face while the sweet potato pie missed its mark.

"The vegan tofu creme pie symbolized the millions of acres of Monsanto's genetically engineered soybean crops and other   'Frankenfoods' coming to harvest this season," BBB said.

Both pie-throwers, whose names were not made public, were detained by security and later arrested by police. It was not   known whether charges would be filed.   A spokesman for Monsanto was not immediately available for comment.

BBB said the incident was the second in two weeks in San Francisco and was designed to emulate the tactics of Belgian   pie-thrower Noel Godin, whose targets have included Microsoft chief Bill Gates and film director Jean-Luc Godard.

Nobel Prize-winning economist Milton Friedman suffered the same fate as Shapiro on Oct. 9, when a BBB activist hurled a pie in his face.