DUBAI, June 1 (Reuters) - Iran on Monday blamed the slow pace of efforts to end the U.S.-Iran conflict on a lack of trust, contradictory positions from Washington and continued Israeli attacks in the region. "Negotiations have started amid severe suspicion and mistrust, and the exchange of messages is taking place in this atmosphere," foreign ministry spokesperson Esmaeil Baghaei said, adding that the two countries had not yet reached a final conclusion.