DUBAI/WASHINGTON, Aug 4 (Reuters) - Conflicting signals from the United States and Iran over the status of talks to end theirfive-month-old warboosted uncertainty on Tuesday, with the latest attack on shipping in the Strait of Hormuz highlighting risks to global energy flows.U.S. PresidentDonald Trump said the talks were under way on Monday, warning of a "last chance" for Tehran to sign a good deal, but Iran denied that negotiations were being held or planned.

Trump confirms resumption of talks with Iran, Strait of Hormuz deal nears-

Remarks come despite Trump saying an agreement with Iran is imminent with negotiations set to begin on Monday.