Dec 4 (Reuters) - Seven Democratic White House contenders participated in a two-hour radio debate on Tuesday. Here are quotes from the three topics discussed in the debate:

* IRAN - Questions on new U.S. intelligence report that said Tehran stopped its nuclear arms program in 2003

- U.S. SEN. HILLARY CLINTON: "I have for two years advocated diplomatic engagement with Iran and I think that's what the president should do. He should seize this opportunity and engage in serious diplomacy using both carrots and sticks."

- FORMER U.S. SEN. MIKE GRAVEL: "Iran's not a problem. Never has been, never will be. What you're seeing right here is something very unique, very courageous. What the intelligence community has done is drop-kick the president of the United States. These are people of courage that have watched what the president is doing, the on rush to war with Iran. And so by releasing this information, which is diametrically opposed to the estimate that was given in '05 ... they have now boxed in the president in his ability to go to war."

- U.S. SEN. JOE BIDEN: "Iran is not a nuclear threat to the United States of America. Iran should be dealt with directly with the rest of the world at our side. But we've made it more difficult now because who is going to trust us?"

* CHINA - Questions related to rising U.S. deficits with Beijing and recent problems with unsafe Chinese imports

- U.S. SEN. BARACK OBAMA: "I actually believe that China will modify its behavior if we actually are tough in our negotiations. Look, we are the biggest market for China. They can't afford to just say, 'See you later.' They're going to have to sell here. If we tell them you have to meet certain safety standards, that you have to enforce certain labor and environmental agreements, they will meet them."

- FORMER U.S. SEN. JOHN EDWARDS: "We have not held China accountable. And the result is the loss of American jobs, the struggling of American families, the struggles of the middle class."

- U.S. SEN. CHRIS DODD: "When we got word that they were sending toys over here with lead paint in them, cat food and toothpaste here, the president had the authority immediately to suspend importation. He wouldn't do it. Had that been a U.S. corporation doing that, their doors would have been shut in 20 minutes."

* IMMIGRATION - Questions about what to do with millions of illegal workers in the country

- OBAMA: "I will make sure that the federal government does what it's supposed to do, which is to do a better job of closing our borders and preventing hundreds of thousands of people to pour in, have much tougher enforcement standards when it comes to employers, and create a pathway of citizenship for the 12 million people who are already here."

- CLINTON: "I think it's important to look at where this debate is often taken to such an extreme, because you'll hear the voices of those saying, 'Deport people. Round them up.' That is absolutely unrealistic, and it is not in keeping with American values."

- DODD: "We need to also recognize there are people at this very hour that are showing up at U.S. Embassies all over the world who are seeking to come here through legal means, and we need to keep them in mind. If it looks as though they're fools to be doing what they're doing, because we're creating virtually an amnesty program in this country, then you're going to have an awful problem around the world." (Reporting by Deborah Charles)

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