The front section of an Iranian oil tanker that has been on fire for days off the east China coast has exploded. <br/><br/>Rescue boats are searching for 31 missing sailors and to retreat and sparking environmental concerns due to the oil spill. <br/><br/>Thirty-two crew members, including 30 Iranians and two Bangladeshis, went missing after the tanker carrying 136,000 tonnes of oil condensate from Iran to South Korea collided with a cargo Chinese freighter and caught fire last Saturday.<br/><br/>So far, no survivors from the tanker have been found and only one body has been recovered. All 21 crew members aboard the Chinese ship were rescued.<br/><br/>