US Federal Reserve chairman Ben Bernanke on Thursday briefed the US Senate\'s Democratic majority on the danger to the United States from the eurozone crisis threatening the world economy, lawmakers said. \"Chairman Bernanke really outlined the European fiscal situation, laid out the vulnerabilities to Europe, the consequences to the United States, and it was very instructional,\" said Democratic Senator Barbara Mikulski. Mikulski gave no further details, but said that she had been \"concerned\" about Europe\'s fiscal health for some time. Persisting rifts between European Union nations over how to battle the eurozone crisis threatening the world economy on Thursday forced the 17-nation eurozone to call a fresh summit next week, officials said. After vowing decisive action to its G20 partners to resolve Europe\'s debt crisis, wrangling between Paris, Berlin and others has prompted the need for a new summit next week, following three days of crunch talks in Brussels this weekend, officials in Paris and Berlin said. \"This is a crucial time,\" Democratic Senator Ron Wyden told reporters after leaving the briefing by Bernanke. \"I continue to believe, given the stakes and the interrelationship between the countries, that calm heads are going to prevail,\" he added. Democratic Senator Bob Casey said Bernanke had provided \"an assessment and an update\" to lawmakers about the crisis. Bernanke spoke at the Democratic senators\' weekly policy luncheon and was not expected to address Republican lawmakers, congressional officials said.