KABUL, Afghanistan — The Taliban have returned to an all-out offensive on the battlefield, killing dozens of Afghan security forces each day, officials say, even as American officials try to keep alive a scuttled peace deal to end the long war in Afghanistan.

The insurgents have ignored appeals for a cease-fire on humanitarian grounds as the fast-spreading coronavirus threatens to overwhelm the country’s feeble health system and wreck an economy already dependent on foreign donations. They accuse the United States of not upholding its end of the deal signed in February, which promised the release of up to 5,000 Taliban prisoners held by the Afghan government in a matter of 10 days, as a prelude to direct talks between the two Afghan sides on a cease-fire and power-sharing.

President Trump spoke over the phone on Wednesday with the emir of Qatar, where the Taliban’s negotiating team is based, about “the importance of the Taliban reducing violence and continuing discussions on prisoner releases,” the White House said. Mr. Trump’s peace envoy, Zalmay Khalilzad, and Gen. Austin S. Miller, the commander in charge of the American and NATO forces in Afghanistan, also traveled to Qatar this month for meetings with the Taliban.

There was no statement from the U.S. side about what was discussed, but the Taliban said the talks had focused on the “complete implementation of the agreement as well as delay in the release of the prisoners.” In the past, violence levels have been a major part of the discussion when the American military commander has participated.