By Mariam Karouny BAGHDAD, July 24 (Reuters) - Envoys from the United States and Iran are due to begin a second round of talks in Baghdad on Tuesday on Iraq's worsening security crisis, following up on a landmark meeting in May between the two rivals. Iranian ambassador Hassan Kazemi-Qomi and his U.S. counterpart Ryan Crocker will lead the talks in the Iraqi capital. Their meeting on May 28 ended a diplomatic freeze between the two nations. Iraqi Foreign Minister Hoshiyar Zebari met Crocker and Kazemi-Qomi separately in Baghdad on Monday in preparation for the meeting but a precise agenda for the talks is not yet known. Washington accuses Shi'ite Muslim Iran of fomenting violence in Iraq. Iran denies the charge and blames the U.S.-led invasion in 2003 for the bloodshed between Iraq's majority Shi'ite and minority Sunni Arabs. "One would hope you would see a change in Iranian behaviour," a U.S. State Department spokesman said in Washington on Monday. "It is up to the Iranians. "We are going to raise the need for Iran to match its actions with its words in seeking strategic stability in Iraq." White House spokesman Tony Snow said explosive devices blamed for the deaths of many U.S. troops in Iraq as well as other weaponry were still coming into Iraq from Iran. "This is an opportune time, at the invitation of the Iraqi government, to revisit commitments Iran has made, saying that it believes in trying to stabilize Iraq. We have seen signs that we think need addressing," said Snow. NUCLEAR AMBITIONS The United States has been leading diplomatic efforts to isolate Iran over its nuclear ambitions but both sides have long stressed that the talks in Baghdad will focus solely on the unrelenting violence in Iraq. The chaos in Iraq has pushed the two countries, which have not had diplomatic ties since shortly after Iran's 1979 revolution, to seek common ground. Crocker and Kazemi-Qomi described the May 28 talks as positive and Iraq has been urging the two sides to meet again. Kazemi-Qomi called the May 28 meeting "a first step in negotiations" but Crocker has said he was less interested in arranging more meetings than laying out Washington's case that Iran is arming, funding and training Shi'ite militias in Iraq. The U.S. military has previously displayed what it says are Iranian-made rockets, mortars and roadside bombs seized in Iraq. Roadside bombs are the biggest killers of U.S. troops in Iraq. Keeping up that pressure, the U.S. military said on Sunday it had detained two suspected insurgents linked to the Iranian Revolutionary Guards' Qods Force. Iran does not officially acknowledge the existence of the Qods Force. The second round of talks comes after the Iranian envoy earlier this month made the first consular visit to five Iranians detained by U.S. forces in northern Iraq in January. The U.S. military says the five men are linked to Iran's Revolutionary Guards and were backing militants in Iraq. Iran has insisted they are diplomats and demanded they be freed but, like Iran's nuclear ambitions, the subject is unlikely to be raised at Tuesday's talks.
