Yemen’s warring parties failed to reach agreement on Saturday to lift a blockade by Houthi rebels of the country’s third largest city, the United Nations said, after three days of talks in the Jordanian capital of Amman. The failure virtually shuts down hopes that the blockade of Taiz will be lifted as it was supposed to be as part of a UN-brokered two-month truce that ends on 1 June. Hans Grundberg, the UN envoy for Yemen, said a proposal had been floated for a phased reopening of roads in Taiz and elsewhere, which would help facilitate aid deliveries and the movement of suffering Yemenis. In…