KABUL, Afghanistan — With the United States weighing a complete withdrawal from Afghanistan by the end of next year, President Hamid Karzai offered a stinging critique of the American-led campaign here, saying that coalition forces had inflicted needless suffering on Afghans.

“They could leave,” he said in an interview with the BBC.

The focus of the war, Mr. Karzai said, should have been insurgent training camps and havens across the border in Pakistan, not “in Afghan villages, causing harm to Afghan people.”

Mr. Karzai has lashed out at the United States and its allies before. But his latest comments, broadcast Monday evening in London and posted online in the early hours of Tuesday in Kabul, came at a crucial juncture. The NATO coalition’s mission concludes at the end of 2014, and negotiations to keep American forces in Afghanistan beyond that point are stalled, according to Afghan and American officials.

Officials on both sides of the talks say they have reached the limits of their willingness to compromise, a sentiment echoed by Mr. Karzai in the BBC interview.