MEXICO CITY: Foreign Minister Patricia Espinosa on Wednesday rejected accusations by several US Republican presidential hopefuls that radical Islamic groups were operating in Mexico.

Several candidates warned of the threat to the United States of militants from Hezbollah and Hamas from within Mexico, in a televised debate Tuesday.

"There's no foundation to support these kind of declarations. We're very surprised to see this kind of debate where such statements are made without anything to back them up," Espinosa told journalists in Mexico City.

During the debate, Texas Governor Rick Perry said: "We know that Hamas and Hezbollah are working in Mexico, as well as Iran," while former Massachusetts governor Mitt Romney said Hezbollah was working "throughout Latin America, in Venezuela, in Mexico ... which poses a very significant and imminent threat."

"With a lot of respect and in a friendly manner we ask ... that there be more care with these type of statements," Espinosa said Wednesday.

Relations between Mexico and its northern neighbor, particularly border security, have often emerged in the Republican debate ahead of party primaries for the 2012 presidential elections, beginning early next year.

Romney and former House speaker Newt Gingrich are currently leading opinion polls.