DOHA, Qatar — Deadly violence surged across Afghanistan as American and Taliban officials started a seventh round of peace talks on Saturday, with high hopes for a breakthrough.

The talks, held in the Qatari capital, Doha, aim to hammer out a provisional schedule for American troop withdrawal in exchange for Taliban guarantees that international terror groups will not be allowed to operate on Afghan soil. Such an agreement is seen as a crucial step toward opening negotiations between the Taliban and the Afghan government over the country’s political future.

A spate of attacks on Friday and Saturday that killed nearly 300 fighters from both sides, according to claims by the Taliban and the Afghan government, was a sign that optimism at the negotiating table might not translate to an immediate reduction in violence, as the rivals seek to use battlefield gains for leverage. Casualty numbers provided by both sides are often exaggerated and difficult to verify.

One of the deadliest episodes took place in northern Baghlan province, where the Taliban killed at least 25 members of a government militia during an overnight attack on their outposts in Nahrin district. Residents and officials described a large number of insurgents amassing for a surprise assault that routed the government militia and the reinforcements that arrived at the scene.