The Trump administration’s direct talks with the Taliban have left the U.S.-backed government in Kabul in the dark, raising concern that any peace deal will lack the public support to work, Afghanistan’s top emissary to Washington warned this week.

The pointed comments from Afghan Ambassador Roya Rahmani were the latest sign of deepening distrust between allies. U.S. envoy Zalmay Khalilzad has stepped up unprecedented direct talks with the militant Taliban amid reports that President Trump is eager to withdraw U.S. forces from what is already the longest war in the country’s history.

Ms. Rahmani told a small group of reporters this week about fears that the emerging U.S. plan will only embolden the Taliban on the battlefield, increasing pressure on the beleaguered government of Afghan President Ashraf Ghani.

“The [Afghan] government does not feel they have been briefed enough” on the Khalilzad talks, the Afghan envoy said. “If a peace [deal] is to be negotiated and is to be durable, it cannot keep going on without the presence of the Afghan people.

“For the Taliban to discuss [peace] on behalf of 35 million Afghans, on what basis are they going to that?” she asked. “They are not our government, they are not our representatives.”

She made the comments weeks after hundreds of Afghan parliamentarians, senators, and provincial and district leaders met in Kabul for the Loya Jirga council of elders to discuss the way ahead for inclusive peace talks. Ending the war in Afghanistan “should be decided by the people who are most affected by this process,” the ambassador said.

Mr. Khalilzad, an Afghan-born U.S. citizen who has held a series of negotiating sessions with senior