A former Taliban commander involved in peace negotiations with the Afghan government has been detained in the United Arab Emirates, according to Afghan officials, who said the arrest thwarts the long-term reconciliation efforts of President Hamid Karzai’s government.

Agha Jan Motasim, the Taliban’s former finance minister, was taken from his family’s home by Emirati authorities about a month ago, Afghan officials said, just as Karzai’s government was growing optimistic about a breakthrough in peace talks.

But in recent interviews, U.S. officials raised doubts about Motasim’s role as a prominent peace negotiator, saying his ties to the Taliban leadership had faded in recent years. The officials added that Motasim’s arrest was unrelated to his role as a peace negotiator. They spoke on the condition of anonymity because they were not authorized to comment on the sensitive matter.

Afghan officials say Motasim was the best chance Afghanistan had to reach a peace deal with the Taliban, which U.S. and Afghan forces have been fighting since 2001. In recent years, he had held meetings with current and former Taliban members, expressing hope for the peace process. He gave interviews to international news media outlets to broadcast his plans for reconciliation.

In the UAE, Afghan officials said, Motasim proved particularly helpful, agreeing to meet with Afghan emissaries in March and attempting to recruit high-level members of the Taliban to the peace process.

“Known and secret enemies of peace in Afghanistan continue sabotaging our peace process,” Aimal Faizi, Karzai’s spokesman, said Thursday. He did not specify who he thought was responsible, but Afghan officials often accuse neighboring Pakistan of abetting insurgents and stymieing peace efforts.

Emirati officials declined to comment on Motasim’s arrest.

Motasim had long been detached from the Taliban leadership — first living in Turkey, where he identified himself as an emissary from the insurgent group, and then in the UAE. Many Western officials had questioned his Taliban bona fides.

For years, one of the biggest hurdles to reconciliation efforts has been finding Taliban negotiating partners who are perceived as legitimate by the group’s leadership, which is thought to be in Pakistan. Publicly, the Taliban has largely dismissed the peace process and referred to Karzai as a “stooge” of the West.

In June, after what appeared to be significant progress, peace talks in Doha, Qatar, were derailed after a Taliban office raised a banner declaring it an outpost of the “Islamic Emirate of Afghanistan,” the name under which the Taliban ruled the country before the U.S.-backed invasion. The Afghan government was outraged.

Since then, Western officials have expressed little optimism about the peace process. But Karzai has pursued reconciliation through his government’s High Peace Council.

Afghan officials say that they have not been formally told why Motasim was arrested but that they have heard explanations from individual UAE officials.

“He was meeting certain suspicious people, and the Emiratis were worried about him,” said one Afghan official who was not authorized to speak on the record.

Other officials said that, even though the circumstances surrounding Motasim’s arrest remain unclear, it is perceived by the Karzai government as a sign of foreign interference.

“We know there are those trying to block the peace process, and they’ve helped arrange Motasim’s arrest,” said another Afghan official, who also spoke on the condition of anonymity.

Karzai saw peace with the Taliban as the potential crowning jewel of his presidency, which is likely to end after the national election process is completed this summer.

“We have asked the UAE government to remove restrictions [on Motasim] and take immediate action for the solution of the problem,” said a High Peace Council statement.

Karen DeYoung in Washington contributed to this report.